I didn't want to put this as a discussion post in its own right, since it's not really on topic, but I suspect it might be of use to people. I'd like a "What the hell do you call this?" thread. It's hard to Google a concept, even when it might be a well-established idea in some discipline or other. For example:

Imagine you're playing a card game, and another player accidentally exposes their cards just before you make some sort of play. You were supposed to make that play in ignorance, but you now can't. There are several plays you could make which would have been beyond suspicion had you made them in ignorance, but if you make them now, they will be seen as suspect and opportunist in light of your opponent's blunder, so you feel obliged to make a less favourable play that is at least beyond reproach.

Is there a term to describe this? It, and various other social analogues, seem to crop up quite a lot in various guises, but I don't have a satisfactory label for it.

Alternatively, does anyone else have a "what the hell do you call this?" they want to throw out to the crowd?