The thing about insanity jokes is that you can’t let the reader see them coming or they flop. It’s also well-trodden joke territory in general, so you have to do something beyond the “ha ha there’s a crazy guy” to make them work. What I tried doing here was to let the reader all of a sudden see it from the perspective of the orderly behind that door. I don’t plan on doing a lot of insanity jokes.
The true stories behind your favorite clip art.
This reminds me of one of my favorite parts of Silent Hill 3. In one of the cutscenes, the player asks an NPC something along the lines of “Are you alright? This place is crawling monsters!” The NPC, being a sadistic smartass, replies: “They look like MONSTERS to you?!” He was joking, but it was still a dick move. One of my favorite ones in video game history.