Bth Street in San Francisco. The curb corners are labeled with street names. For the blind to feel with their canes? To show the Department of Public Works where to return street signs that have run away? I'm not sure. But this is my favorite of all the corners. It's actually 5th Street, and if you look very closely, you can see where a prankster modified it before the concrete set.
I have this possibly false memory that this sign was featured in a Zippy strip.