After a couple of beers, you turn to your drinking buddy and ask, "Wanna play quarter targets? I'll bet you a quarter you can't roll a quarter down your face and hit a target!"
You take a quarter from your pocket, set it on a bar napkin or paper placemat, and draw a nice dark ring around it with a #2 pencil. (make sure you're touching the quarter with the lead of the pencil) Then you show him how it's done: holding the quarter lightly between your thumb and forefinger, you let it roll down his forehead, over his nose, and let it drop towards the ring. Then let him try it. If he fails (and he will, after a couple of beers), tell him, "You need more targets!". After each failure, take the quarter and draw another ring on the placemat. Eventually he succeeds, and takes your quarter.