Chompy appears in many episodes as a mascot and semi-celebrity in the city of Dimmsdale. Some of his misadventures include participating in a belching contest, chasing the Mayor out of City Hall because of a goat-eating revelation, and even became "scarred for life" when he gazed up on a nude Timmy Turner.
Chompy is a white goat that wears a red collar with a bell around his neck. He speaks in bleating, and the Mayor and other characters seem to be able to understand him. Like Poof, he speaks in a manner that is hard to understand (since he is a goat) but some of the characters strangely understand him clearly.
He first appeared in Dream Goat!, where he was first seen by Timmy Turner while on a guided tour along with Vicky the Babysitter in Dimmsdale City Hall. Chompy is the town mascot, who is kept in a cage inside the City Hall. While most of the other kids were uninterested in the goat, Timmy noticed Chompy looked sad and miserable. He then read Chompy's mind and found out that Chompy wanted to be free and have a mate. Deciding that this would make Chompy happy, Timmy wished for Chompy to be free. When the Mayor of Dimmsdale noticed that Chompy had gone missing, Vicky was immediately blamed and arrested due to her being in his cage. This caused Timmy to feel severe guilt, which ultimately lent to him confessing to freeing Chompy to the townspeople. They formed an angry mob and proceeded to chase Timmy, but Chompy appeared alongside a mother goat and two goat kids he had sired while gone. The Mayor and townspeople saw how much happier Chompy was while free, and he and his family were allowed to come and go from Dimmsdale whenever they pleased. Unfortunately for Timmy, he is grounded for lying about the incident in the first place.
After that, he made a lot of short appearances, but no other episode had him involved in the main plot, and his family does not appear again at all. Chompy frequently appears with the Mayor of Dimmsdale in his subsequent episodes. He was the other contestant in a belching contest in the episode, "Mooooving Day", but ultimately lost to Timmy Turner. In the episode, "Vicky Gets Fired", Vicky used photos of the Mayor at a goat meat eating convention to blackmail his friendship with Chompy, which caused Chompy to chase the Mayor out of the city. This incident was later referenced again in "Crocker Shocker", when the Mayor is seen talking to a psychiatrist about his and Chompy's misunderstanding. The psychiatrist assured him that she would take care of that by hypnotizing Chompy to ensure that this wouldn't be a problem for the mayor and Chompy. In "The Masked Magician" he was mentioned in a newspaper headline being acquitted of charges.
Chompy even had a minor role in the live-action movie Fairly Odd Movie. He is still the mascot of Dimmsdale after thirteen years, and appears alongside the mayor at Dimmsdale Park when the oil tycoon Hugh J. Magnate was presenting plans for redeveloping the park. After Timmy Turner saved Tootie and the Dimmsdale Dogwood from the bulldozers and the chainsaws, Timmy wished for Chompy to eat Hugh J. Magnate's pants in order to humiliate him and drive him out of the park so that he wouldn't threaten Tootie.