Little Johnny is always being teased by the other neighbourhood boys for being stupid. Their favourite joke is to offer Johnny his choice between a nickel and a dime.
Little Johnny always takes the nickel.
One day after Johnny takes the nickel, a neighbour takes him aside and says “Johnny, those boys are making fun of you. Don’t you know that a dime is worth more than a nickel, even though the nickel’s bigger?”
Johnny grins and says “Well, if I took the dime, they’d stop doing it and so far I’ve made $20!”
Credit: Thanks Bill