Dungeons & Dragons: 1st Edition Monster Manual (part 1)
Steve: There's nothing wrong with Lurkers. When I DM I nail Keith with these all the time. Great cave monster.
Zack: It has ceiling tiles on its underside!
Zack: So what kind of animal evolves ceiling tiles on its stomach?
Steve: I saw on the History Channel about these crabs in Japan that look like samurai faces. They used to be just regular crabs with a few oddball ones, but fishermen would always throw back the ones with samurai faces so now all of them have samurai faces.
Zack: What show were you watching on the History Channel about crabs with samurai faces?
Steve: I don't remember. It was about evolution though. The crabs with the samurai faces evolved.
Zack: Okay, let me see if I have this straight. You're saying that because there are crabs in Japan with samurai faces, something I don't even know that I can believe but I will take your word, that explains lurkers.
Steve: Well the ones that didn't have tiles underneath wouldn't look very good in the room. They'd remodel the castle and chase them out. But if they had the tiles nobody would mind.
Zack: No! No, this is getting worse. They don't flip a dungeon and change the monster living on the ceiling.
Steve: You could with a ladder.
Zack: You don't live with a monster on your ceiling.
Steve: It could be in a cave.
Zack: What good are the ceiling tiles on its stomach in a cave?
Steve: Maybe it was in a castle and then they remodeled it into a cave.
Zack: I give up. I give up, Steve. You win.
Steve: Don't be like that.