Even Greener Pastures

Never "weasel words", but I have heard and used the word weasel more than just to describe the animal.  Someone who loses a bet or had made a promise that they no longer want to fulfill we say they are trying to "weasel out" of their commitment or promise.  It is really a rather descriptive phrase.

Think of grabbing a weasel and how they would twist and turn and writhe to get free.  That is the mental or verbal gymnastics of someone weaseling out.  Be careful using the phrase, you can use it good naturedly among friends but strangers might take it as an insult, just under calling them a liar.