![Cement warning](http://farm7.static.flickr.com/6109/6228198032_78f9732625.jpg)
Soon as I saw the “warning” in the cement, I immediately thought of Fight Club:
Tyler Durden: Did you know that if you mix equal parts of gasoline and frozen orange juice concentrate you can make napalm?
Narrator: No, I did not know that. Is that true?
Tyler Durden: That’s right. One could make all kinds of explosives using simple household items.
Spotted on the roof of the Art Institute on Chestnut St.