A phrase said to a person when they are bitching about an issue that they either can not or will not do anything about. It is often used in place of the phrases "what are you going to do about it?" or "I don't care."
Dude #1: Bro, you ate all of my Dunkaroos. I was saving those for my Bat Mitzvah.
Dude #2: Hey, Fucking cry about it!!
Dude #1: Dammit! I have to write a 50 page report on the mating habits of the blue-nosed land squid by tomorrow and I haven't even started.
Dude #2: You know what you should do, dude? Go cry about it.
Dude #1: Hey Mike is pretty pissed you keep banging his girlfriend. He said He's going to kick your ass.
Dude #2: Whatever, tell that faggot to go cry about it!