look up any word, like plopping:
 
1.
A basic bowel movement. Usually reserved for high-volume output. Especially after lunch when you feel like it will take a great feat of strength to go poop.
I was just in the 3rd stall pushing mud, so wait about 30 to 45 minutes before you go in there.
by Neil Larocca June 06, 2005
 
2.
The act of defecating. The issuance of fecal material from the colon, via the shit chute, into (or upon) something either utilitarian or symbolic.
"Hey in there - what's taking so long? I hope for your sake you're not pushing mud! We're out of a-wipe and crapper spray!"
by Commode Mouth September 17, 2006
 
3.
To take a shit
Guy1: She'll be back in a sec. She's pushing mud.

Guy2: That's a myth. Girls don't do that.
by wreck it & respect it December 19, 2008