Just tossing this out for chewing, how's about a Waymarking Game or Sign category for signs that contain typographical errors and grammatical errors?
I don't have any images to share in demonstration but I can give you a couple examples. The town of Hazleton, PA is spelled incorrectly. It's become an accepted misspelling. The original fire truck in Rensselaer, IN has the town's name spelled wrong. An ex-boyfriend's father owned a karaoke bar and one of his window decals was a motto that had an incorrectly positioned apostrophe.
My preference would be for instances that are visitable so there'd be some amount of permanence to them... but those are details. I'd like to get some discussion on the concept first and then we'll see if it's worth going deeper.