Gentleman's Agreement
Let’s say our neighbor’s lawn needs to be cut. And let’s say we really want cookies. Now let’s say we offer to cut our neighbor’s lawn if he’ll bake us some cookies. He thinks that sounds swell, so we shake on it and agree to each fulfill our end of the bargain this coming Saturday.
This is what’s known as a gentlemen’s agreement. It’s not a legal or binding arrangement—no contracts were signed, no lawyers were present—but we both risk damaging the relationship if we decide to renege. Our motivation to keep our promises to each other is less about the threat of legal action and more about keeping our word and maintaining a high level of mutual trust. Our goal is to increase the chances of future mutually beneficial arrangements happening; maybe, for example, this cookies-for-cut-lawns thing could become a regular thing.
Gentlemen’s agreements can happen on a much larger scale than that, though. Back in the 19th century, it wasn’t at all uncommon for national governments to make deals with each other sealed with nothing more than a verbal promise (and maybe a glass of cognac). And some people and organizations still conduct business this way to this day; sometimes it’s easier to get stuff done when certain informal agreements and arrangements have already been put into place.
Is this shady? Not necessarily, but just like anything, it can be if the folks involved use it to do illegal things or unfairly influence certain outcomes.