When Cartman has Asperger's Syndrome, he has his own way of dealing with the disorder. By calling it "Ass Burgers" and planting burgers in his butt of course.

South Park Season 15 Episode 8 Quotes

Nurse: Why are there hamburgers in your underwear?
Cartman: Are you serious? You're saying I have Aspergers?

That's just your brain levels adjusting back to the real world.