Kung Fu

Two kung-fu masters were carrying on about their respective skills. "Why, my reflexes are such that you will not believe," boasted Master Foo and drawing his sword, he sliced at a passing fly, which promptly dropped dead in two pieces.

"That's nothing," said Master Koh. Drawing his sword, he made two deft cuts at another passing fly.

Master Foo was highly amused. "What are you talking about?" he sneered. "That fly is still flying."

"Ah yes," replied Master Koh, "but now it can never have children."