A person who is rude, obnoxious or vulgar; a jerk or asshole
Commonly used by someone to refer to a person that is telling them things they don't want to hear
Laura: I'm sorry, I was busy.
Mike: I'm at work all day and when I get home the first thing I have to do is clean. Why are you never able to save me that trouble?
Laura: I do have other things to do, you know.
Mike: Like what, watch QVC, eat cookies, and sleep?
Laura: You know what, you're a real smack!
Mike: And you're a useless piece of shit! Now that we've stated the obvious, where's my dinner?