We had a substitute gym teacher last year that was having a totally serious conversation with our class about diabetes, but then...he said "diabeetus"
Me and one other guy couldn't contain our laughter fast enough so we just kind of ended up making sputtering noises and everyone turned to look at us
Totally tried to play it off as inconvenient simultaneous sneezes (*whispering* "bless you!") which I'm pretty sure no one actually believed
