It's a gentleman's agreement until one side ceases to be one.
English: Two persons shaking hand (Photo credit: Wikipedia ) I never really understood 'gentlemen's agreement'. It assumes that both parties will act gentlemanly, honoring an unwritten pact. This is bound to fail because as human beings, we are subject to change and will change eventually. That change will make one party realize the advantage of not continuing to honor the agreement. Add to that the idea that going back against something that is unwritten is much like going against nothing at all and you have a recipe for failure.