Mr. Rustworthy

"“Don’t look now," “but a bunch of kids are out in the parking lot filling up our cars with low-fat cottage cheese!”"

- Mr. Rustworthy

Mr. Rustworthy is the music teacher at Jerome Horwitz Elementary School. He is a nice teacher who likes children, especially George and Harold (both facts are stark contrast from most of the other staff), but not food fights. His name is a pun to the word "mistrustworthy."

Captain Underpants and the Wrath of the Wicked Wedgie Woman
He witnesses the children having a food fight and the football team destroying the teacher's lounge.

Captain Underpants: The First Epic Movie
He is a minor character in the film, not doing anything particularly notable.