Mastearbathing 

The art of masturbating while crying in a bathtub.

I was so done, I was mastearbathing for a good hour

Mastearbathing by SuperFatDragon January 2, 2019

masturbathing 

The act of jacking off while in the shower.

Why were you taking so long in the shower?

Oh, I just got done masturbathing.

masturbathing by cabbage206 August 15, 2009

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

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

Masterbating Monkey 

A primate creature who masterbates.

"Monkey Masterbation Spotting" has become a hobby in the South American State of illinois. A well known competitor in the sport of of Monkey Masterbation Spotting is Fred Phelps, a very vocal and fanatically religeous biggot.

The monkey wrapped his primate hand around his primate pink penis, and masterbated furiously untill he fell out of his tree. Fred Phelps watched in glee as he photographed the event so he could show the pictures to his family.

Masterbating Monkey by Gordon Freeman October 31, 2004

Masturbathing 

The act of a nice shower becoming a masturbation session

YOU - Dude, get out of the shower, you've been in there for over half an hour!!
ME - Sorry man, I was bathing but then I started masturbathing

Masturbathing by enroiv December 6, 2010