Etiquette

Just be glad you aren't playing chess in the middle ages:

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The Dangerous Elephant: 12^th Century, Possibly Sicily

Chess has never been an entirely peaceful game. When a medieval player became angry during a match, he would sometimes pick up a chess piece and hurl it at his opponent's head. Occasionally this killed his adversary. If you were going to pick a piece to do some damage, this would be a good choice, Boehm says. This piece was likely an elephant, the predecessor to the bishop. The two protruding nodules at the top represent elephant tusks. "Some people say the sort of stylized elephant [nodules] gave way to the bishop because the bishop wears that hat with the two points," Boehm explains."

http://www.slate.com/slideshows/arts/strange-old-chess-pieces.html#slide_8