An Attitude Check is the act of giving someone anal sex to remind them to check their attitude because it has been out of line lately.
It is often used to teach partners in a relationship that they are not all that sweet as they claim. The universe doesn't revolve around them because their getting drilled in the anus.
Friend: Bro, I heard your girl has been giving you a lot of trouble lately...
Me: Yea man... I don't know what to do...
Friend: Bro, it's simple... just give her an attitude check.