He is a fat, white skinned, human-like conscience with a blue top hat and a tiny pink nose. He has blue jeans, a red undershirt and black suit and shoes. He also has white gloves.
Role in episode
Stimpy sends Jimminy Lummox to Ren since he had been doing many bad deeds earlier. Whenever Ren does something bad, Jimminy appears and punishes him, usually in a way of severe violence--such as hitting him with a banjo, a wrench or dropping a car on him.