When I saw "The impossible pullup, I was expecting something a bit different."
We used to do this thing called "the impossible situp"..... choosing out a hefty guy from the group and daring him to try it. The idea was that they'd lay down, and get ready to do a situp, except there would be a folded up towel put across their forehead and held down to the floor on either side of their head. Only a really in-shape dude could pull that off, right?
When they'd try to do the situp, straining with all their might, we'd let go of the towel and their face would fly up.... directly into a mass of shaving cream.... or someone's ass, depending on how much we liked the guy.