Shamerbate 

When a woman induces feelings of shame and self loathing in a man for masterbating

You wouldn’t be able to shamerbate me if you actually put out

Shamerbate by Madnax22 October 31, 2017

Showerbate 

The Act of furious Masturbating during a shower

Damn Showerbating isnt funny anymore

Showerbate by Wilitus July 29, 2005

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

shaturbate 

To shit and masturbate at the same time

I was sitting on the toilet, and I decided to shaturbate to this picture of Jenny

shaturbate by Poloshirts64 May 7, 2014

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

Showerbate 

When one masturbates in the shower

I love to showerbate in cold water

Showerbate by triangle_boy June 24, 2011

Shatterbate 

(v) The Act of Masturbating while taking a shit

"Shit, I really had to pinch one out when I was at Six Flags. I just decided to shatterbate in the bathroom"

Shatterbate by Shrek'sBrotherinlaw November 19, 2014