The way you greet a friend when you are feeling a little bit retro and a little bit geeky.

Asks what another has his attention on. What is he thinking about or busy with? "Up" in this case is using a slang definition from around the 1930s meaning: occupied with, busy with.

This question is often used to start conversations with.

What you say when you do not really know what to say.

What's new; What's going on? wussup

The question often asked, when a foulness beyond belief emanates from where the sun don't shine.

This is a combination of "what's goin on?" and "what's up?". I said this accidently the first time I talked to this guy on the phone. I was trying to be cool and confident but inside I was nervous as hell! LOL

What me up means, you asked someone to update or brief you about the current affairs or relevant local or global affairs.