Old Filthful

Old Filthful is a geyser of sewage in the sewers. Like in real life, it goes off periodically in an exact amount of time. However, unlike Old Faithful, it bursts sewage instead of hot water. It is most likely the same sewage that is in Lake Mutagenic. It is apparently a popular tourist attraction for mutants. However, Leela found it disgusting after her parents showed it to her.