During our quick trip to San Luis Obispo, walking through the streets, we found the Bubble Gum Alley. That's right, an alley whose walls are almost completely covered with chewed gum! People go there and leave their "mark" sticking their chewed gum on the wall!
This alley is next to a bar that tells the story of gum and the alley, but we didn't go there to check (neither had the courage to walk between these walls...)
Disgusting, but interesting!