If someone is sitting on the floor in front of you and you are sat above them you rap your legs around their head and shart. Slippery poop will then dribble down the back of the persons neck simulating a mudslide.

A jack off buddy (from 'cum' /'come', meaning 'semen', and 'companion'); a friend that you get together with for sessions of solo or mutual masturbation
Variant of: cumpanion (from 'companion' & 'cum'); jack off buddy & wank bud & JO buddy
Similar to: fuck buddy