"This is important in this case because of the use of the defined term “Burglar.” Contracts to do something illegal are ordinarily unenforceable (e.g. collecting on an illegal gambling debt). But here what matters is not that the parties used the word ‘burglar’ but rather what sort of meaning they assigned to that defined term. As we shall see, the contract doesn’t require Bilbo to do anything illegal (or at least not obviously illegal), and so the contract will probably not fail for use of a questionable term."
—On the legality of Bilbo Baggins' contract, one of the more successful things Peter Jackson decided to get cute with for no reason, RADAGAST WHERE IS YOUR DIGNITY YOU ARE A WIZARD.