House: You eat a lot of beets. You have an electric toothbrush, and you sleep less than six hours a night.

Flynn: That's impressive.

House: The red betamine from the beets stains the plaque deposits on your teeth which are then swirled by your spinning toothbrush. The heavy lids and your prematurely aging skin tell me that you're carrying a major sleep debt.

— You Don't Want to Know

You Don't Want to Know is a fourth season episode of House which first aired on November 20, 2007. Kutner and Cole take time out to see a magician, but the show nearly ends in tragedy when the magician has a heart attack during a trick. When Kutner tries to get House interested in the case, House figures the magician just screwed up and challenges Kutner to prove that there's something wrong with the magician before taking the case. However, when the magician takes a turn for the worse, all the symptoms point in the wrong direction until House remembers Cameron's favorite zebra.

Meanwhile, to keep the applicants busy, House offers one of them the opportunity to keep their own job for a week while putting two others on the bubble. He challenges them to steal Cuddy's thong. Astoundingly, Cole's the winner and the rest of the team starts to suck up to him to get him to choose someone else for the axe. However, when Cole makes his choice, House figures something's wrong.

Finally, House gets through Thirteen's aura of mystery when she gets mad at herself for doing something clumsy, and House does some digging to find out the reason behind Thirteen's drive and ambition that contradicts her seeming fatalism.

The episode explores the essence of magic - whether it's better to know how the trick was done. It explores House's obsessions with mysteries, even ones that don't involve medical issues. In addition to the patient's case, he wants to know how the "tricks" were done, including the one carried out by one of his fellows. The non-medical problems are all characterized by the same issue - someone knows the answer, but not House, and he can't use his skills to figure them out.

Kutner and Cole are at a magic show and a reluctant Cole gets the chance to help the magician with the Chinese Water Torture Chamber Trick. However, while the magician is in the cell, he starts bleeding from his mouth. Cole realizes its not part of the act, calls for help from Kutner, and gets the magician removed from the chamber.

House is distressed that he still has five candidates but no patients. Kutner tries to talk him into taking the case of the magician, who had a cardiac arrest just after entering the water. House agrees to allow Kutner to do tests, but says he will fire Kutner if he can't find anything wrong. House gives the rest of the applicants a challenge - to get Cuddy's thong. The winner gets immunity and gets to nominate two people, one of whom will be fired.

The applicants discuss whether they should go through with it, but they all know Amber will.

Thirteen comes in to help Kutner with the patient, but all of the magician's tests seem to be normal. The magician entertains them with tricks.

Taub and Amber are hanging around Cuddy. Amber proposes an alliance, but Taub isn't interested. They're both planning to get her thong wet. Taub tries to spill coffee on Cuddy, but fails. Amber's gambit is to help at the clinic.

Kutner goes to Foreman for help when he can't find anything wrong with the patient. Foreman suggests an MRI of the patient's lungs.

Meanwhile, Amber calls Cuddy to the clinic and then sets off a sprinkler. She succeeds in flooding the clinic, but Taub has waylaid Cuddy so she doesn't get wet.

Kutner tells the patient he might have a fungus in his lungs. However, as the patient is put in the MRI, he starts having extreme abdominal pain. Kutner spots signs of internal bleeding. Kutner and Thirteen report to House that there must be something wrong with the patient. Taub comes in with a thong, but House knows it's not Cuddy's (it's the wrong color), and figures out that Amber supplied the thong (and that she's not wearing underwear). Foreman gets them back on topic. House realizes the patient was screaming because he had swallowed a metal key - something that magicians often carry in their mouth to use in escape tricks. He goes down to surgery and finds it. House takes Kutner off the case and confronts the patient, saying he was hurt by the water cell trick because he's incompetent. However, the magician denies screwing up the trick. He astounds a then-unimpressed House with a magic trick that puts the chosen card on the side of the glass outside the room. The magician then gets a severe nosebleed.

Because of the nosebleed, House agrees the patient is really sick. He puts the thong challenge on hold. However, Cole comes up with a thong, but House and the other applicants thinks he's lying. They start a differential. Taub thinks it's cocaine. House orders an environmental scan and a heart blood vessel biopsy. House then confronts Thirteen about hiding a medical condition because she dropped a file. Thirteen denies anything is wrong.

Kutner and Taub go to the patient's home. They think Cole's lying about the thong. However, Taub finds rabbits.

House asks the patient how he did the trick. He refuses. House pretends to cut his intravenous line (by holding a short length of tube together with the actual line), but the patient picks the Vicodin from House's pocket. He tells the patient he has tularemia from his rabbits.

House realizes Cuddy isn't wearing any underwear, and she blushes when he mentions Cole. He goes to find Cole to ask him how he did it. Cole says it was mostly prayer, but refuses to discuss it further - it would ruin the magic. Kutner comes in to say the patient has passed out, is losing a lot of blood and it isn't tularemia. House tells the patients Cole has won the challenge. While they do a differential, House notices Thirteen's hand is shaking. They decide cancer is most likely.

They prepare the patient for another MRI. He says he's going to die by that time tomorrow. Amber asks Cole who he will nominate to be fired. Cole's concentrating on the MRI. They spot internal bleeding all over the place, but no masses. They realize the patient might be right about dying.

Cole wonders if the sense of doom might be a symptom, but House dismisses it, saying it's no more impressive than his guessing all their pagers might go off. Kutner thinks it might be tainted blood from a transfusion. Foreman notices the patient's immunoglobulin levels are low and thinks it's amyloidosis. Suddenly, all their pagers go off.

Cole and Kutner go to the patient who has another seizure. Kutner suggests that Cole pick someone else. Meanwhile, House is discussing with Wilson how Cole got the thong. Wilson suggests Cole had sex with Cuddy. Kutner comes into report that the patient's kidneys are failing. House thinks it's amyloidosis and orders a fat biopsy. House notices Thirteen's hand's trembling. He gives Kutner two hours to check the blood to see if it's tainted.

Taub comes to Cole to bribe him - $5, 000. Cole isn't impressed and hands back the money. Amber, Kutner and Foreman can't find any blood problems. The fat biopsy was inconclusive. They can't do blood cultures because there isn't time. House orders them to treat for amyloidosis, but Foreman stops them - he thinks the treatment's too dangerous even though he thought it was amyloidosis. House decides to give himself a blood transfusion to show there's nothing wrong with it.

Thirteen is monitoring House and he confronts her about her mother - he found out she died and Thirteen admits it was from Huntington's disease. Thirteen figures she might have it, but House tells her that she's probably just taking in too much caffeine - he switched out her decaf. Thirteen has not been tested for the Huntington's gene, and House is astounded. Suddenly, Thirteen notes that House has a fever.

They start discussing what's wrong with House. They discuss doing a biopsy on House because the patient will hemorrhage if they biopsy him. House denies he's sick despite his sweating. However, when he stands up, he feels dizzy and realizes his coffee has been drugged by his team. Cole and Thirteen prepare to biopsy House. Cole wonders why she hasn't asked him to give her immunity from being fired. House wakens and asks if the patient's still alive and Thirteen proceeds with a liver biopsy. House realizes it was Thirteen who drugged him, but she notes he drugged her too. After Thirteen leaves, he grabs a bottle with Thirteen's DNA to do a test on it for Huntington's.

Wilson tells House that they're ready to irradiate the patient in preparation for a bone marrow transplant. They start talking about blood types, and Wilson wonders how House knows his. Suddenly, House thinks of something. He goes to the patient to ask him how he did his tricks, but the patient's still close mouthed. He tells the patient isn't dying - he was given the wrong blood type, type AB instead of type A. That's why he got worse immediately after his surgery, but it also explains his earlier heart attack. The patient was making antibodies that didn't match his blood type because he has an autoimmune disease - lupus. The tests picked up the extra antibody and instead of testing type A, he tested type AB instead. The wrong type blood caused the bleeding and organ failure. He orders saline, type A blood, and steroids.

Cole nominates Amber and Kutner to be the choice to be fired. House asks why Kutner was nominated - he did well on the case and he's Cole's friend. House figures out that Cole made a deal with Cuddy to nominate whomever she wanted as long as he got immunity - Cuddy dislikes Kutner as he's a liability to the hospital. House fires Cole instead for giving Cuddy power she didn't already have. The other applicants say their goodbyes to Cole, but Kutner, clearly hurt by his friend's betrayal, leaves the room.

Thirteen confronts House about testing her for Huntington's. They don't look at the test results, with House dropping it in a trash bin.

It's finally lupus. Lupus is very uncommon, and is less common in men. Its symptoms are also non-defining and can point to many other conditions. Lupus also happens to be the gag inside episodes where it's mentioned, usually the joke is that whatever the patient has, it's never lupus.

• Setting off one sprinkler head with heat does not set off the whole system. Each valve is controlled by a heat sensitive vial that will break and release water at the appropriate temperature. It will set off the alarm as well, but as long as the other sprinkler heads are intact, they will remain dry.
• An MRI of the lungs is rarely useful. It's a much better idea to do a CT scan or a Ventilation/perfusion scan.
• Blood types are tested before every transfusion. If there's uncertainty or there's not a half an hour to perform the test, the patient's given type O which is both the most common type and the type that won't cause a transfusion reaction.
• It was a really bad idea to give House narcotics to knock him out. Narcotic addicts have a higher tolerance and a high enough dose to render him unconscious would be close to the dose necessary to kill him. A benzodiazepine would be a better choice.
• Thirteen's pendant changes position between shots, sometimes appearing on top of her shirt, but at other times being partially hidden by it.
• House was wrong about how blood is tested: Blood typing is done on blood cells and antibodies. Blood type is tested by ABO typing. This is done routinely by separately mixing a sample of the patients blood with anti-A and anti-B antibodies and seeing if the blood reacts with the antibodies. If the blood reacts with both antibodies, the patient has type AB blood. If the blood reacts only with anti-A or anti-B, the patient has type A or type B blood, respectively. No reaction with the antibodies would indicate an O blood type. When you have blood type-A, it means you have anti-B antibodies. Type-AB has no antibodies for A nor B. A patient's plasma is also tested for antibodies against the A and B antigen. If they are group A and make anti B, they should react against B cells. If they are type B, they will react against A cells. Type O reacts against both A and B cells while type AB reacts with neither. For type specific blood to be given, these reactions against the patient's own red cells and their plasma against other cells should match. More info on the tests.

• The Chinese Water Torture Cell was developed by Harry Houdini in 1911. Contrary to the biographical picture of his life, Houdini did not die performing the trick.
• The blood in the tank rapidly rises, but blood is actually more dense than pure water (causing the blood to sink) and is approximately the same density as water from a public source (causing the blood to cloud or move slowly up or down).
• Mamma Mia is a musical comedy based on the music of ABBA.
• Flynn's death prediction was actually developed by Canadian Magician James Randi who, every day for a couple of decades, prepared a card he carried on his person saying he would die on the given date. He eventually stopped and, as of December, 2019, he was alive and well at the age of 91. Randi died at his home on October 20, 2020, at the age of 92. His death attributed his death to "age-related causes".
• Wilson notes that a relationship between Cole and Cuddy is still "Legal in the blue states." In United States politics the Blue States are those that generally vote for Democrats and tend to have liberal laws. New Jersey's generally considered a blue state. He could also be referring to the states involved with the Union during the American Civil War - states that fought to end slavery.
• Kilimanjaro is a set of three dormant volcanoes in Tanzania. It's the highest mountain in Africa and one of the few places in Africa where snow falls.
• House realizes that Thirteen's mother is dead, and she retorts, "So is Grover Cleveland." Grover Cleveland was the 22nd and 24th president of the United States from 1885 to 1889 and from 1893 to 1897, respectively.
• The Pitcairn Islands are a small inhabited group of islands where the residents are primarily descendants of the mutinous crew of the HMS Bounty. It currently houses about fifty people, which makes it the least populated distinct territory on Earth. The majority of Bounty descendants left Pitcairn and moved to Norfolk Island, off the east coast of Australia.
• When House confronts Thirteen about the possibility she has Huntington's, she counters that he could "get hit by a bus tomorrow". Later in the season, House is on a bus which gets hit by a garbage truck.
• Jennifer Morrison and Jesse Spencer were both credited for this episode, but didn't make an appearance.
• MAGIC TRICK ALERT - In the Chinese Water Torture Trick, there's no hidden key. The shackles are fake and open under pressure. There's a small air cavity at the very top of the chamber that allows the magician to take a breath. The top of the chamber is false and can separate from the rest of the chamber when under pressure. However, due to the constraints of the water box, the trick is still dangerous to perform.
• The end of the episode contains an In Memoriam to supervising sound editor Barbara Isaak, who passed away on July 21, 2007 from ovarian cancer.
• MAGIC TRICK ALERT - The card on the other side of the glass trick requires an accomplice. The magician "forces" a card on the volunteer, distracts them from where the card is affixed, then throws the deck at the glass.
• The word amyloidosis is repeated fifteen times during the episode.
• How Stella Got Her Groove Back is a 1998 romantic film based on a novel by the same name. It concerns a 40-year-old woman who has an affair with a 20-year-old man while on vacation.
• The elimination system in this episode is a reference to Big Brother, in which one contestant that wins a challenge will nominate other contestants for elimination. "Who is on the block?" also references this.
• The reference to "Sophie" is to Sophie's Choice, a 1979 novel later made into an Academy Award winning film.