This one comes from season 10 episode 9 called “Mayored to the Mob” when Homer becomes the personal bodyguard of Mayor Quimby. Homer takes the kids to Springfield “Bi-mon-sci-fi-con” and we see Comicbook guy wearing this shirt. That’s all I got. Oh and guest appearance from Mark Hamill.

Here’s the link to the product as a pin, but you can view the design on multiple items if you’re interested.