The act of turning your forsekin inside out and twisting your penis several times to then unleash it spraying smegma in a swift-like fashion. This is usually done in the center of a group of people at a party or classroom.
Guy 1: "Hey! Did you see what I did at the party last night?"
Guy 2: "No, what did you do?"
Guy 1: "I managed to pull off the most epic smegmachine gun of all time!"
Guy 2: "Dude, no way!"
Guy 1: "Yeah! I even managed to hit my Grandpa who was fast asleep on the couch!"
Guy 2: "No, what did you do?"
Guy 1: "I managed to pull off the most epic smegmachine gun of all time!"
Guy 2: "Dude, no way!"
Guy 1: "Yeah! I even managed to hit my Grandpa who was fast asleep on the couch!"
by Grandpa Bob January 16, 2014
Get the Smegmachine Gunmug.