Some amusing Wills and Trusts laws:
In California, an engagement ring is a conditional gift. If the person who receives the ring breaks off the engagement, they can be forced to return the ring. In common law, it even depends on who breaks off the engagement. That means that if the person who gives the ring breaks off the engagement, the receiver doesn't have to return it!
Also, if you give a gift because you think you're about to die, but then you survive, you can get the gift back!