You see a lot of odd road signs when you're out on a bike. A grammatical oddity is this noun chain on Charing Cross Road, just up from Cambridge Circus: PEDESTRIAN CASUALTY REDUCTION SIGNAL TIMINGS EXPERIMENT. Curiously, this nominative blitzkrieg isn't on Google Street View.
I saw this odd fingerpost in Leicestershire in 1997. Emerging from a sociable pub lunch I saw a sign to somewhere evidently called PISSWELL. There's no such place, and the picture isn't Photoshopped; someone had been making mischief with a screwdriver, creatively rearranging letters. It's really PICKWELL.
Best of all is this celebrated sign in rural Kent, where the village of Ham is close to the town of Sandwich. Apparently people keep nicking it.