English to Polish Social Sciences Slang

It is in "The twenty three" book by Linwood Barclay.
Police detective Duckworth goes to speak with Victor Rooney - a murder suspect.

"He looked at me as though I was slow - witted, and there were times when I thought I was. "You gotta be kidding me."
"I can understand why you might want to put this town behind you," I said. "but I`d have thought you`d have done it three years ago."
"Sometimes it takes a while to get your act together." He finished the toast, wiped his mouth with paper napkin, balled it up, and tossed it onto the porch. He leaned back, arms outstretched, palms on the porch boards."YOU JUST COME BY TO SHOOT THE SHIT?"