Usually followed by a joke or an untruth to show you were just kidding; it's kind of like saying "I'm just yanking you're chain"
Guy 1: "Hey man, you're girlfriend gave me head last night"

Guy 2: "What?! Are you serious?!"

Guy 1: "Nah, I'm just pissing on you're tits haha"
by Ry'and'seabass July 31, 2010
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