A common response to the age-old question, "What the fuck are you doing?" or in slang terms, "Fuck you doing?"

wasting time; clownin around

To fuck around. To Say something to someone that ain't true.

what martha stewart said when she heard she was going to prison.

To be extremely angry. see pissed

Calling someone out who's trying to game you. You can't bullshit a bullshitter.

You just don't understand how bad I want this thing. You're just messin around while I'm over here serious about the shit. While ya bullshittin, I'm over here tryin to seriously explain what "why ya bullshittin" means.