There's a little fellow named Billy who hangs out at at the local Deli.
The owner Tim doesn't know what Billy's problem is, but the other boys like to tease him. They say he is two bricks shy of a load, or two kangaroos short in the top paddock. To prove it, sometimes they offer Billy his choice between a Dollar and a Two Dollar coin.
He always takes the Dollar, they say, because it's bigger.
One day after Billy grabbed the Dollar, Tim got him off to one side and said, "Billy, those boys are making fun of you. They think you don't know the Two Dollars is worth more than the Dollar. Are you grabbing the Dollar because it's
bigger, or what?"
Billy said, "Well, if I took the Two Dollars, they'd quit doing it!"