Sadly, I've gone through life not knowing this word:
a medical condition in which strong emotion or laughter causes a person to suffer sudden physical collapse though remaining conscious.*While we've all experienced intermittent cataplectic shock, Kay Underwood lives with it every day. The 20-year old lives in Barrow upon Soar, England, where she tries to avoid the sorts of amusing situations that the rest of us look forward to.
According to a Daily Telegraph article, Underwood momentarily collapses every time she laughs. And it's not just laughter that can do it to her: "Exhilaration, anger, fear, surprise, awe and even embarrassment can also cause sufferers to suddenly collapse on the spot."
A certain Dr. Andrew Hall said, "I had one patient [the attacks] happened to whenever he had an overwhelming feeling of smugness."
As for Underwood, in another interview, she reported that sometimes her friends "good-naturedly" tried to make her laugh. Good-naturedly?! If MY friends tried to make me laugh, I'd try not to laugh. Just to spite 'em!
Failing that, I'd suffer sudden physical collapse though remaining conscious. (And while incapacitated, I'd contemplate the best medicine for laughter.)
*ORIGIN late 19th cent.: from Greek kataplēxis ‘stupefaction,’ from kataplessein, from kata- ‘down’ + plēssein ‘strike.’