The sport involves putting two ferrets inside one’s trousers, having first tied one’s trouser cuffs firmly to one’s ankles, lest the ferrets escape. The competitor then cinches his belt tightly, and the clock is started. Competitors cannot be drunk or drugged, nor can the ferrets be drugged. In addition, competitors cannot wear underpants beneath their trousers, and the ferrets’ teeth cannot be filed or otherwise blunted. Competitors can touch the ferrets, but only from the outside of the trousers.
(via Best of Wikipedia)