I've seen it a couple times a long while ago. Isn't that the one where he gives a report about poop molecules and smelling things = eating them?
From what I remember it seemed the parents were pretty messed up and negligent of the kids who in turn seemed to live kind of tragic lives.
No, I don't think so, his parents were negligent, and they were the typical Baby-Boomer bad parents, letting Donnie call his sister at the dinner table a Assfuck, and she tells him to "Suck a Fuck"
Donnie calls his mother a Bitch, and he is on meds. Floods the Private school, tells his teacher to shove a book up her ass (parents laugh when told this), and burns down a Pedo's house.
Oh, and the classic discussion of a Smurfette Gang bang, wher Donnie reveals that Gargamel had created the smurfs, and that they are asexual.