The Sewer People are a street gang who can be usually found on the Fourth Island of Paper Thin City, initially found to be infesting the entire island, and can appear in the Third and Second Islands as well. They are infamous among residents in Paper Thin City, with some describing the Sewer People as gruesome and merciless. Their main base can be found in the Sewer Entrance across the Hardware Store, but one can't access it until they have acquired the Sewer Key.
Very little is known about how the Sewer People came to be. Many rumours about their origins circulate around Paper Thin City, especially in the Fourth Island, where they're speculated to be a failed government experiment, a cursed group of people, and even aliens from outer space. Females among the Sewer People are called Sewer Wenches. They are known to have a hierarchy, with the king leading the entire pack. Their speaking abilities have been impaired heavily, as suggested from their constant growls from most of them, although some are capable of speaking understandable English.
How to get the Sewer Key
The sewer key located at Fourth Island, which you must have director cut, You can get the key on night, in front of S.I.T. (Stick Institute of Technology ) and near the fountain. Those five green people / sewer people have the key, you must fight the Sewer King and with his friends. In the fight, they don't have ranged weapons (Pistol, AK-47, Blast Cannon, Double-Barrel Shotgun, and Minigun). Upon death, they will drop the sewer key.
After you got the sewer key from sewer king, you can go to the Sewer Entrance located in front of the Hardware Store. After you finish killing sewer people in the sewer place, you will be rewarded a Fuel Cell that will be used to craft/make the Modified Flamethrower.