Here we have a teachable moment: "borborygmus" is the scientific term for "stomach growling" (plural borborygmi, pronounced /ˌbɔrbəˈrɪɡməs/; from Greek βορβορυγμός). It comes from the ancient belief that digestion was the purview of a grouchy dwarf named Borbory residing in the stomach. His grousing at the lousy job he had pushing food around your innards, instead of bowling with his cousins, was heard as a growling sound, as opposed to the more dignified thunder that his bowling relatives caused.
I think that's right; it's late and the mind wanders, y'know? Anyway, the Stapling Ceremony seemed like a good way to wrap up the whole Cartoon Camp story and gives everybody a chance to dress up. The kids might be dressed as their titular superheroes, though that undercuts the fact that Petey isn't a big fan of superheroes- he's more likely to enjoy Jimmy Corrigan or Pim and Francie. Which is not to say his taste is sophisticated, just grimmer than a taste attuned to the gaudy spectacle of superheroics.
By now superheroes are mostly beyond parody. Stuff like the Tick and Herbie Popnecker pushed the absurdity of the tights little world about as far as it could go while still being funny. But the actual genre is its own best parody. I'd originally used the name "The Kaboomerang Kid" in Andre's comic title. A quick googling let me know that Kaboomerang is already a superhero who throws exploding boomerangs, of course.