Although there has been much debate about the true definition of "The Tough Mudder", the official definition is insurmountable.

The Tough Mudder
/THē təf məd•dər/

While penetrating a female anus with the penis, the penetrator enters a free hand into the vaginal canal. Once accomplished, proceeds to masterbate his penis through her vagina while occupying her anal cavity.

Street names/slangs include;
Brownie beater
Fecal fap
Fisty fap
Mr.Hankey hand job
Mud tug
Over under
Reach through
Smelly jerk
1. The other day Nicole and I pulled off the tough mudder, let me tell you, it is quite possibly the hardest event on the planet.

2. Bro, when Ashley is shmasted face she always wants that brownie beater...I ain't mad.

3. "I let Jimmy do the #mudtug once, now all he wants is a smelly jerk:(" said Becky to the marriage counselor.
by lasvegascashew October 17, 2014
Attempting to perform anal sex while you have whiskey dick.
I tried to put it in her butt last night after the bar but it turned into a round of tough mudder instead
by Gtoaster July 31, 2018
A shit taken after a night of hard drinking that is particularly difficult to deal with. Unlike the traditional morning-after shit (which is an even-flow of black, smooth tar), the Tough Mudder’s consistency is that of mud mixed with clumps of ribs and chicken wings that act as grappling hooks inside the anus. Putting a foot up on the tub and screaming as though in labor is a typical method of dealing with this difficult shit. Not to be confused with the Labatt Splats.
"I had a Tough Mudder this morning that nearly killed me. I was on the can for a good hour AND I got a nose-bleed while pushing..."
by Ernest Saves Hemmingway III August 31, 2012
Guy1: Did you hear Michael completed the Tough Mudder Challenge?

Guy2: Yeah he's a Tough Mudder Fucker.
by XxMayhem6xX February 19, 2012
Aaron: “Where are you off to Janelle?”
Janelle: “I need to tame a beast, I’ve had a tough mudder brewing all morning. If I don’t hurry up it’s gonna turn into a mud slide!”
by Andos Hastos January 12, 2022