noun. A PG-rated--though gross--motherfucker.
Real citation: "Listen here, you smegging smegged up mothersmegger. I'm not going to take this kinda of smeg, got it smegger? So why don't you take your smeg and smegg it up your smeg, you smeg of a smegging smegger."
(KrazyTwister, Oct. 9, 2004, http://z1.invisionfree.com/forums/Zentrotem_Wars_Board/index.php?showtopic=54&st=75)
Made-up citation: "Who's more of a geek: A mothersmegger, motherfreller, or motherfraker?"