n. ejaculate; cum; sperm
Originates from Smodcast (Kevin Smith and Scott Mosier podcast) Episode 91 at the 52:44 mark where guest Malcolm Ingram credits uber-producer Scott Mosier with the genesis of the term.
"After the Nut Mud leaves my dick, I'm done. I'm very self-loathing."
When your banging a chick so hard she farts out a little shit on to your balls. Also see Mud Flaps.
"I was fucking that chick so hard she blew out a little nut mud."