A slang term for the anus, or as I like to call it, butthole. It is the tight sphincter that cuts the pooh as it leaves your body. Sometimes it is also the opening that men like to place their cocks inside for great pleasure.

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