To engage in the activity of sleeping. This usually occurs after long periods of strenuous activity and/or sex. However this usually refers to a more deep sleep than that of a light sleeper.
Nigga I be hustlin all day. Fo realz, man I can't wait to hit muh shawty up, do tha dirty dirty and then get muh Z's on.... fo real.
The forbidden grade that you receive when you know you are a fukking idiot and didn't revise or even listen to anything or anyone and probably have been adopted by a bunch of nonces
To sleep. I'm not sure of how many ways to use it though.
If you were sleeping you wouldn't be "z'ing."
The only way I know how, or have heard anyone use it is in the example.
Slang: I'm going to cop me some z's
Translation: I'm going to get some sleep