The tension around the ass when holding in a fart for a protracted period of time.
when you have
to fart but for some reason
ie you're stuck in an elevator, in bed with someone you DONT fart around etc
example- i was stuck on the elevator
when i realized the steak'ncheese for lunch
was about to blow
my ass out, but the hot chick from down the hall was on the elevator
so i had to hold it for 17 floors before i could
hop out and let loose...if i had waited to get out any longer
would have brought
me to my knees in pain.