it's strange that you use "shitty fucking" in place of "magical best friends forever"

I'm also in the "Karl is real and self-aware" camp, I figure he just doesn't censor those goofy passing thoughts that most people dismiss or keep to themselves, because he knows it entertains people.

And if he really is sharing his internal monologue on the show, that implies that Karl is an extraordinarily humble and good-hearted person, who allows his friends to tease and mock him not because of low self-esteem or desire for approval, but because hey, they're just havin' a laugh, and havin' a laugh with your friends is what its all about, innit?