A sexual act whereby one man expells his payload into the the behind of another man who has a poop "on deck." The man with the goodies in his rectum squats over the other man, who in turn pulls on this man's erect penis, mimicking the lever of a soft serve ice cream machine. The feces/semen mixture is released, just like a chocolate/vanilla soft serve ice cream! The act is concluded when both men yell, "Soft serve swirl, coming right up!"
by soft serve guy December 8, 2007