Idiots Cannot Catch Colds

"Subordinate: Hey boss, if you're trying to infiltrate a hospital, you should just go in as a patient!

Bang: That's an excellent idea, but I've never been sick. I don't even know how to get sick..."

- Blaz Blue: Calamity Trigger

A common superstition in Japanese culture: stupid people are immune to colds.

When invoked, may lead to a Delayed Reaction of "did you just call me an idiot?"

This has an equivalent in French, where Coryza is commonly known as "Rhume de cerveau" (brain cold), which people without a brain obviously can't catch. The English phrase "too slow to catch a cold" may or may not be related. If there is any Real Life explanation, it may be that idiots are too stupid to realize they even have a cold, then ignore it until it goes away.

Anime and Manga
"Gintoki: "That damn Zura...I always thought he never caught colds because his body resisted viruses, but it's the opposite! His body absorbs viruses, which means his immune system was strengthened to a point when he can never catch colds!""
 * When Kagami has the flu in Lucky Star, Konata mentions off-handedly that since she's an idiot, she's not afraid of catching a cold. After some discussion on whether the flu is an upgraded version of a cold, Konata acts disappointed that she hadn't been contradicted on the "idiot" part.
 * Plus, she's not an idiot so much as a slacker and does get a summer cold not long after.
 * There was some more discussion of that in later manga, when Kagami got the flu the second time-- Miyuki mentioned the other variation of this trope: idiots catch colds in summer. Of course Miyuki quickly apologized. On the other hand, Yutaka kept catch colds summer or winter, so is she an idiot or not?
 * In the manga, Kagami points out that Tsukasa never seems to get sick...
 * Hidamari Sketch: Miyako invokes this (referring to herself) when Yuno falls ill, and even remarks on how unusual it is for her to catch a cold even though she she claimed she's an idiot while being interviewed for admission to this very prestigious high school.
 * In the same chapter, it was found out that all the eight students sitting next to Miyako fell ill with the 'flu. That said, like the Konata example above, Miyako is more a Ditzy Genius than a real idiot.
 * Pani Poni Dash
 * In Eyeshield 21, Otawara is the only one of the Ojou White Knights to never miss a single practice, because, well, idiots don't catch colds.
 * Kanon twists this into "Uguu~ never gets sick,"
 * Lampshaded in Urusei Yatsura when Ataru gets sick.
 * Sailor Moon: A sick Luna told Artemis that he was safe because idiots don't catch colds. He was offended.
 * In the Excel Saga manga, Iwata catches a cold at some point and Sumiyoshi says something like "so idiots do catch colds!"
 * In Ranma 1/2 when Kuno tries to get rid of his cold by passing it onto Ranma, Ranma remarks that he thought Kuno was too stupid to ever catch one in the first place.
 * An episode of the Kirby anime revolves around this when King Dedede is the only one in the land not to catch a cold, and desperately tries to to prove he's not an idiot. That episode had a few Japanese things that outsiders would find weird, such as everyone who got sick wearing a medical mask.
 * In Bleach, after Ichigo he asks Orihime if she's ok. She responds "Well I'm pretty tough too! When I was a kid I never caught colds."
 * Also used in Detective Conan.
 * Doumeki from XXX Holic once tries to coax Watanuki out of the rain by assuring him that the "Fools can't catch colds" clause doesn't apply to dumbasses.
 * In One Piece, after Nami (the smartest Straw Hat at the time) gets sick, Luffy asks Usopp and Sanji if being sick is unpleasant, and both respond that they have never been sick before.
 * America hasn't even HEARD of colds, so...
 * Apparently retconned, though, to represent the current recession. Worse, America's "cold" is so bad that it spreads.
 * Hanajima says this about herself in Fruits Basket.
 * Mentioned on Bunny Drop when Rin catches a cold. Daikichi mutters to himself that he's lucky he's an idiot.
 * Seto Kaiba says this to Jonouchi on one occasion in ~Yu-Gi-Oh!~.
 * Kengo's older sister Mayu in Monochrome Factor is joyous when she catches a cold, proving that she is not an idiot (though her actions say otherwise).
 * Subverted in Ouran High School Host Club in a (manga-only) particularly memorable arc when resident Idiot Hero Tamaki Suoh gets a fever, much to everybody's shock, gets delirious, and ends up kissing Haruhi on the forehead as a gesture of 'parental affection'. He, of course, forgets the entire exchange when he gets better.
 * In Kyou no Go no Ni Ryota has all the symptoms, but has to be told by someone else that he has a cold, leading the others to speculate that the saying actually means that an idiot wouldn't realize if he caught a cold.
 * In Beelzebub Furuichi says these exact same words to Oga after the latter sneezes and wonders if he has caught a cold.
 * In the Soul Eater manga, Tsubaki comes across Black☆Star thinking outside at night and expresses concern: "You'll catch a c... well, no, you probably won't, but aren't you cold?"
 * In the second season of Strike Witches, Yoshika reveals to the doctor during her physical that she's never had a cold before.
 * In Skip Beat, Ren denies that he's coming down with a cold and brags that he's never been sick. Before the arc's over he's sick as a dog, proving his only stupidity deals with his romantic feelings. His unawareness of this trope is nice foreshadowing of.
 * This trope is hilariously played with in one episode (165) of Gintama when everybody (save for Shinpachi who's forced to take care of them) is sick with colds. When the air in his home is polluted by Hasegawa who's wearing numerous viruses, arrives the biggest idiot of them all, Katsura. Yet somehow he doesn't even look like Katsura anymore. He has turned into Obama look-a-like "Ill Smith" for no apparent reason, who repeats the YES WE CAN at the end of his sentences and he can suck the diseases from everybody in a blink of an eye. He cures their colds, The Messiah has arrived!


 * Also in earlier episode when Gin is sick, Kagura gets jealous of him, claiming that she wants to be genius as well and he shouldn't get cocky just because he has a cold and she doesn't. Gintoki deadpans "an idiot. This girl truly is an idiot" to no one in particular at this comment. Several times. By the end of episode though, she and Shinpachi have caught colds too.
 * Used as an early gag in Yaiba. Subverted when, after invoking this trope, Yaiba still catch a cold for playing in the snow.
 * While it wasn't alluded to in-sries, it is worthy to note that the titular Irresponsible Captain Tylor caught a cold once. It feeds the Epileptic Trees and makes you wonder if Tylor really is an idiot or a brilliant man.
 * Sugi acted surprised in Girl Friends when she learned that Akko caught a cold. Sugi thought that the Book Dumb Genki Girl was immune to colds.
 * Unspoken in Prunus Girl when only Maki catches a cold after getting caught in the rain with Aikawa.

Live Action Television

 * In Kamen Rider Kiva, Yuri Aso comes to this conclusion after Otoya Kurenai uses the IXA System without suffering the detrimental side effects it demonstrated on its previous user. In fact, he's well enough to dance around in a Shout Out to the actor's musical past.
 * During the case of the aptly named dopant in Kamen Rider Double, Akiko is sick with a cold during the whole two episodes and uses this excuse for why she didn't cover her mouth when she sneezes at Shoutaro. It of course leads Phillip to a Wiki Walk about the origins of the phrase. At the end of the arc, Shotaro sneezes, causing both Akiko and Phillip to re-evaluate their past comments.
 * During the Gekiranger / Boukenger teamup, Mele mentions that the Monster of the Week gets sick the least out of all their troops. He's also very sensitive about being called an idiot.

Video Games
"Amitie: I didn't get an antidote.
 * Touhou has Cirno, who is doubly protected against colds by being 1.) an ice fairy, and 2.) the resident Baka. Naturally, numerous fanworks have lampshaded this trope.
 * She once got a cold due to excessive heat. Intentionally in fact, to prove that she's not an idiot.
 * Yamame Kurodani also tends to lampshade about the immunity of idiots in fanworks.
 * A character accuses Moses Sandor from Tales of Legendia to be "too stupid to catch a cold" when someone comments on his rather light choice of clothing regardless of where they go, cold places and all.
 * In a "Teach me, Miss Litchi!" segment in Blaz Blue, Bang is planning to infiltrate Litchi's clinic so he can get closer to her. One of his subordinates suggests going in as a patient, but Bang is an Idiot Hero... see the quote at the top of this page.
 * Referenced by Kyrie in Magical Girl Lyrical Nanoha As Portable: The Gears of Destiny after her Idiot Hero sister somehow managed to resist the virus she gave her.

Kyrie: But... the virus!

Amitie: Things like that... Can be taken cared of by Fighting Spirit!

Kyrie: Fighting Spirit...?

Amitie: Fighting Spirit! With it overflowing from my body, a mere virus won't beat me!

Kyrie: That's the same as the saying "Idiots don't get colds"!"

Western Animation

 * An episode of The Real Ghostbusters was set in Japan. In one scene, a Japanese schoolboy is taunted by other children by stealing his hat. The head bully says "You can't catch us! You can't even catch a cold!" At first, it seems that they're making a pun that probably only works in English, but makes sense when you remember this trope.
 * The animation for The Real Ghostbusters was actually produced in Japan (by the same studio as Lupin the Third), so the use of this trope may not be coincidental.