mud diving 

It's like muff diving, but in the back.

Sandy was on her period, so I went mud diving instead

mud diving by smile420 May 2, 2014

Mud Diving 

Forming a hole in the mud filling it with water and having intercourse with it.

Let's grab the waterhose head out back and go Mud Diving

Mud Diving by Mjb02 June 5, 2018

Muddilingus 

Noun: the act of going down on a woman who wipes her anus back-to-front after bowel movements.

Muddilingus on your mom is best performed 4 hours after she has eaten Indian food.

Muddilingus by YUsostoopit January 13, 2018