It is the filthy area never whiped between a man's balls and his anus. Legend has it that shit nuggets dwell in this region. (Watch your tongues ladies.)

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