Probably the most over-used, unintelligent and
pathetic comeback phrase and/or insult ever imaginable in all of humankind.
Not only is the useage commonly meaningless and inaccurate, it's a piss-
poor and half-assed attempt at trying to offend someone who is clearly clever and better at insulting you than you are at insulting them.
The term is also pretty
annoying, petty and pitiful.
Ex:
Person #1: I see that you are overweight, unlikeable and have a horrid personality... Who taught you to be the way that you are, you skanky slut?
Person #2: Your MOM!
Person #1: I suppose that makes sense, since you've never met with my
mother or have ever been acquainted with her.
Whatever. You
suck at making insults.
Person #2: Um... shit, I guess you're right.