mathterbating 

Doing math for fun, enjoyment, entertainment and/or to pleasure ones self.

Dude1: Hey! whats that nerd over there doing with that calculator?
Dude2: Probably mathterbating
Dude1: Dude! sick he could at least go to the bathroom to do dat
Dude2: Gotta do what you gotta do

mathterbating by SeakingFuckYeah! March 4, 2008

methturbating 

The act of masturbating, high on methamphetamine s.

Jim was too busy methturbating to answer the phone.

methturbating by thugnasty24 December 19, 2009

Mouthterbating 

Slang for autofellatio, or when you masturbate with your own mouth.

Last night I was mouthterbating. My mouth still tastes salty!

Mouthterbating by Mouthterbating August 30, 2014

masterbating with a cheese grater 

Doing a task that is not a good idea

Moving this piano without help is like masterbating with a cheese grater.

masterbating with a cheese grater by matt1975 September 10, 2012

mathdurbating 

1 pleasuring ones self during math class

2 how a person with a lisp would say masturbating

did you see that girl mathdurbating 4th period?

mathdurbating by Fiendish August 31, 2005

masterbating 

Expertly jacking off.

Guy 1:Man, I think steve's masturbating again.
Guy 2: From the sound of it, he ain't just masturbating, he's MASTERbating.

masterbating by Sir Fizwheel Humperdink October 5, 2007

stealth masterbating 

When one wacks off as quietly as possible so as to not disturb the people in the same room.

Sam: I hope no one notices I am stealth masterbating
Girl friend: Sam ... are you wacking off!!!!
Sam: Oh Shit!

stealth masterbating by themanwiththeplan9192 April 4, 2010