Sidewalk Appreciation

Listen up, you silly human. You're the kind of person who probably trips over their own feet. This joke plays on the idea that sidewalks literally keep people out of the street. It's a pun, because we don't usually thank sidewalks, and we don't think of them as actively keeping us out of danger. It is silly to thank an inanimate object like a sidewalk but it makes sense, because it does its job well.