After finishing dinner at a Connecticut restaurant, two diners got more than a butter mint when a waiter, apparently miffed by a $2 to $3 tip left on a $50 check, attacked them with a knife. They only suffered minor injuries, but no doubt tipped much better after that. While violent cases of waiter rage are rare, the 1989 incident points to waiters' sticky reliance on tips for income. In some states, restaurants are only legally required to pay as little as $2 or $3 an hour. So if a server earns $30 in tips on a bad night, he...