When I first ran across that one, I noticed a few...odities. I found out after searching the artist that he includes them in all his panels. If you look by his signature, the number there indicates how many oddities there are. Like an alien in a spaceship, or a pipe, or a stick of dynamite.
There's all kinds of nifty stuff for sale in that shop! I think the "IDIOT" bumper sticker, "Buy One, Don't Be One" is one of my faves.