2 definitions by Grandpa Bob

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!"
by Grandpa Bob January 16, 2014
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A natural disaster caused by an extreme excess of smegma concealed in one's own foreskin. Usually caused by not cleaning your foreskin on the regular or from dietary problems resulting in a sudden growth of smegma.
Bill: Hey man are you going to the game tomorrow?
Fred: Nah man my family and I are getting out of town before the Smegmageddon gets here.
Bill: OH SH*T I GOTTA GET OUTTA HERE!
Fred: Yeah dude, it's pretty tragic.
by Grandpa Bob June 28, 2016
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