Special:Badtitle/NS90:Forum:Trope Talk/A Possible New Trope Type

I know it's not really necessary to go through the forums to discuss a potential category, but I was thinking of a new performance trope (something I might call "One-handed Piano Player", about people who don't know how to play piano and are pretending to do so for the camera, and who forget to do anything with their left hands other than set them on the keyboard) and mused that it wasn't an intentional thing, but something we might call an Accidental Trope -- a trope that comes about because of common circumstances across multiple productions, not because of deliberate choices by writers or directors.

So I was wondering -- what do we already have that might count as Accidental Tropes? Special Effect Failure came immediately to my mind as a possibility, but once it did, my internal index crapped out. Does anyone have any other suggestions?