A belt signifying that one has achieved the highest rank in the culinary arts.
More accurately the black belt represents the mastery of the art of cooking, as there are degrees of black belt-- first, second, third, fourth, and Mr. T.
There is only one way to earn a 'black belt', and this is by competing in the annual death-match cook-off. No one actually gets killed, mind you (at least not intentionally), but losers often wish they had. The cook-off consists of a series of rounds, and during each round the candidates duel against each other. The winner of each cooking duel goes on to the next round, and the looser is laughed at and gets pelted with cabbage by the spectators (The tighter does not participate, but looks on with approval). The winner of the last round, as may be expected, wins a black belt, and in fact several more to hand out to fans, friends and family, or to sell on eBay.