In one episode, Truffles mentions that she has fibromyalgia. Fibromyalgia is an illness that, among other things, is characterized by chronic pain. No wonder she's so cranky.
In "The Moldy Touch", Mung tells Chowder that he once let Fungol use him because he wanted to impress his cooking master. Then in "Won Ton Bombs" we find out that his cooking master had deemed him a "failure for life" when he was young. No wonder Mung wanted to impress him - he was trying to redeem himself for his failure.
B) Gazpacho makes Chowder sign a waiver saying he wasn't responisble for his death. Funny enough, but at the end he sounds like he "killed" many other children before. Add in the contract and the possible Norman Bates interpretation and you get one really creepy friend of Chowder's.
Speaking of Gazpacho, no one has ever seen his mother, but he spends most of his time talking about her, and how she puts him down. His mother may be dead, and he constantly talks about her as his only means of remembering her and coping her loss, he even dressed as his mother at one point, not unlike Norman Bates from Psycho.
Actually, we do see her once, in the episode "Gazpacho!", but she is only seen from the back and the view is somewhat blurry.