This is a complicated, yet hilarious prank. First you will need a blindfold, 1 person, and 1 dumbass. You convince this dumbass that they cannot do a sit-up
if you're pulling them down with a blindfold. When they're about to do a sit-up put the blindfold over them and have the other guy quietly step above the dumbass with his shorts down. When the dumbass starts doing a sit-up pull off the blindfold and they will end up with a face full of ass. Try this one, it's pretty damn funny.
Bob: After we did the English Ham on Todd (or English-Hammed him) he wouldn't go over to our parties anymore.
Steve: Hahaha, yeah, well Todd's a dumbass.