To be sarcastically proactive is to be active in what you're currently or about to do as well as being sarcastic about it. This is mostly found in people with either sarcastic or emo-like personalities.
"Oh there she goes again, being sarcastically proactive in shelving those boxes..."
"Hey Mike, quit being sarcastically proactive and be ACTUALLY proactive."
"Why is everyone in the room saying I'm sarcastically proactive? All I did was place the pens in the envelope box..."