shitsterbate 

to masturbate on the toilet while taking a shit

there are some good porn mags in the bathroom I couldn't resist getting my shitsterbate on just now.

shitsterbate by james___ March 20, 2008

Shitsturbate 

To masturbate oneself while taking a shit. Simultaneous masturbation and defecation. The ultimate dual release.

After years of marriage, Carl's wife finally figured out her husband takes an excessively long time in the bathroom because he loves to Shitsturbate.

Shitsturbate by Eaton Holgoode April 28, 2016

Shitsturbation 

A simultaneous performance of shitting and masturbating, often done in public restrooms.

Kayla: Wow, I heard some really weird noises when I was using the restroom. Sounded like someone was really enjoying their dump...
Michael: They were probably undergoing Shitsturbation. It's like a self-performed blumpkin with your hands.

Shitsturbation by gofgirl983 December 17, 2011

shasterbate 

shitting while masterbating

person number 1: "oh wow Justin the football player, takes a long time in the bathroom"
person number 2: "hes probably masturbating while he shits"
person number 1: "haha, Justin shasterbates"
person number 2: "hahahaha thats clever. shasterbate!"

shasterbate by shexcelent December 1, 2009

Shiterbate 

To go to the restroom, informing everyone you intend to take a shit, and remain in the restroom for an extended period of time while actually masterbating

Scott: Where is Kevin?
Andy: Oh he is in the bathroom, has been for 20 minutes, said he was taking a shit.
Scott: Oh, he must be going to shiterbate.

Shiterbate by Nazgul4591 November 1, 2009

shisturbate

To masturbate while taking a massive shit.

Last night, I became aroused while taking a shit, but since I was so pressed for time, I decided to shisturbate.

shisturbate by THE SHLEEPER August 7, 2009

Showsterbate 

To perform the act of masturbation in the shower

At camp, ethan showsterbated which wasn't cool because it was the only open shower.

Showsterbate by Riley Langburt February 18, 2009