I have seen some weird expressions in lessons-files from www.princeton.edu. Even a russian didn't understand this:

Что слышно? = what's up?

I suppose it is kind of slang or something.
Does the understanding of some expressions depend on where the person come from, socially, geographically etc.?

Some other expressions were:

Нахал(ка)! = Jerk
мнe некогда. = I'm in a hurry
нe спрашивай = don't ask! (answer to Что слышно?)