The Marshmallow Test - Kids are left in a room alone with a marshmallow, saying that if they wait long enough, they’ll get ANOTHER when the surveillor comes back. Hilarity ensues.
There’s apparently nothing like watching a kid squirm over a marshmallow. My favorite is the red-headed girl, who just eats the marshmallow as the proctor is walking out the door. After she’s done, she takes her plate, gets up, and walks to the door.
This is a perfect microcosm of the human condition. You can have a little satisfaction now. Or you can discipline yourself for a greater reward. Sadly, most people just eat the marshmallow.