The Nega Chin's Lair is the headquarters of the evil super villain, the Nega Chin.
This evil lair is where the Nega Chin lives and plans his evil schemes from. It is located in a swamp, and the entire lair can be submerged and hidden beneath the waters. It is, in fact, a parody of The Hall of Doom from the Saturday morning cartoon Superfriends. Like the Nega Chin's Lair, The Hall of Doom was the headquarters of the villains in the show, Superfriends.
The Nega Chin's lair is shaped exactly like his head, and the Nega Chin symbol on its chin is a door that opens up to allow access, as does the mouth for those that can fly.
When Timmy wished for the entire world to be like a comic book, this lair appeared on Earth, within a short distance of Dimmsdale, as Timmy and his friends, along with the Crimson Chin, were able to get there without superpowers. Other villains such as the Bull-E, Doctor Crocktopus, and The Baby Shredder were also taken here so they could assist to the Nega Chin. Timmy tried to get Cosmo and Wanda to unwish his wish, but Nega-Chin cutted him off before he could finish his sentence, causing all superheroes to be removed from the world. Dr. Crocktopus then trapped Cosmo and Wanda in an anti-magic bubble, preventing them from using their magic to get rid of the villains. The villains then take Timmy's godparents away to Nega Chin's lair, but later Timmy and his friends devised a plan to get into the lair with the help of the everyday heroes. The janitor hid everyone inside his trashcan while he went inside as a "weak human janitor here to clean their super powerful weapons". As soon as they got to where the villains are, Timmy and his allies popped out of the trash can, but the villains disbelieved that Timmy and his friends could win. Nega-Chin decides to take a bath of evil while the fight is going on. However Timmy and his friends used their ordinary powers and teamwork to defeat Nega Chin's allies. Nega Chin is shocked that they were able to beat his allies, so Nega Chin tried to attack them with his Nega-Vision but he missed, and his attack hit the anti-magic bubble, freeing Cosmo and Wanda and allowing them to wish everything back to normal. Nega-Chin later learned from Timmy and the Crimson Chin that the reason why he keeps losing is because the author of the Crimson Chin comic book series makes it that way.