Tommy opened a small shop selling bagpipes and guns.

One day a tourist stops in and out of curiosity asks, "So how is your strange business going?"

"What do you mean strange?" Asks Tommy.

"Because you sell only bagpipes and guns!" Replies the tourist.

"So?" Says Tommy.

"Well, let me put it this way, what do you sell the most, bagpipes or guns?"

"It evens itself out.” Said Tommy, “Each time a customer buys some bagpipes, one of his neighbours is sure to buy a gun."