In The Hobbit, Bilbo Baggins signs a contract with a company of dwarves to serve as their burglar in their quest to reclaim the Lonely Mountain from a dragon. Lawyer James Daily analyzed the contract in detail for Wired.

Even in the book’s version we see an issue: the dwarves accept Bilbo’s “offer” but then proceed to give terms. This is not actually an acceptance but rather a counter-offer, since they’re adding terms. In the end it doesn’t matter because Bilbo effectively accepts the counter-offer by showing up and rendering his services as a burglar, but the basic point is that the words of a contract do not always have the legal effect that they claim to have. Sometimes you have to look past the form to the substance.