This thread is great... and gave me quite a chuckle. When I think of funny signs, I think of one I saw many years ago... probably 15 years. We were just driving around looking for photo ops, and there was a "Dead End" sign right by a cemetery. As a side note there, that same day 15 years ago, I fell in love with the scene from high on that hill overlooking a river and a quaint little town... railroad tracks, etc. And I thought "How I'd love to live up here!) but it seemed a total impossibility... now I do. I see that scene from my front windows every day.
One day, when I was working in Ghana, I was wandering by the sea-front in Accra and taking a few photos. There was a small and rather pretty lighthouse and I thought I'd take a picture of it. Only when I got right up to it did I see the (very small) notice threatening anyone that took photos of the lighthouse with all sorts of nasty penalties. Quite why, it's impossible to say, but I moved along a bit sharpish.