There was a little town which had its own town idiot who used to hang
 out at the local corner market. The boys from town would constantly
 tease him, saying that he was two bricks shy of a load, or two
 pickles short of a barrel. To prove it, sometimes they would offer the
 town idiot his choice between a nickel and a dime and he would always
 take the nickel -- and they would laugh!

 One day after he grabbed the nickel for the umpteemth time and the
 boys left the store laughing, the store owner took him aside and said
 "You know those boys are making fun of you don't you?  They only offer
 you a dime or a nickel because they say you don't know which is worth
 more.  Why do you keep grabbing the nickel - don't you know a dime is
 worth more?"

 The town idiot looked at the store owner with a big grin said, "Well,
 if I take the dime, they'll stop doing it, and so far I got $20 from
 them!"