Loki's Wager

Loki's Wager is a logical fallacy and form of extreme equivocation.

The story goes that Loki made a wager with some dwarves, and bet his head. Loki lost the wager, and when the dwarves came to retrieve his head, Loki asserted that they could take it, but they were not entitled to any part of his neck. There are some parts which both parties agree are head, and both parties agree are neck, but neither could agree where exactly one ended and the other began. As a result, Loki kept his head.