Happy Tree Friends?
Heheh, okay serious answer: Nothing. There are no kid shows that handle those themes. You're confusing "childish" with "for kids". Adult immaturity is never meant for kids... just immature adults (and maybe teenagers). I'm starting to think you created a topic for the sole reason of ripping on Family Guy. That's called "begging the question" and is most known for being a dishonest tactic.
---
Now, if we were to take the spirit of the question: A cartoon sold as having adult themes but is really just for kids:
My Little Pony: Friendship is for Neck Beards. Okay, technically it was originally sold as a kid's show, I guess (I'm not really sure). But the internet made it into such a weird "for adult people" thing. And the first time I heard of the show was in tandem with the brony thing. So it was sold to me as a cartoon that was aimed at adults in the guise of a children's show.
Oh yeah, by the way... it's spelled "disguised".
And as a fan, in my youth, of the original My Little Pony movie things, I was, at the same time, sure I would like it and afraid I'd be a brony. But no, there were no adult themes. It was all about kiddy social problems and spoon-fed morality lessons aren't entertaining.