Mr. Larson is a one-time character that only appeared in the episode "Nursing a Grudge". He is a teacher in Tommy amd his friends' school and is subject is science. While having a science test, Gus tried to find a way to skip it, so he put a wig full of lice on his head, which allowed Mr. Larson to tell him to go to the school nurse and thus, getting rid of him. Excited over this, he gave the pupils candy, sent them to recess and cancelled the test altogether.