masturbate
wank
jack off
Stroke the Salami
a date with Pam and her five friends
the five finger knuckle shuffle on the one-eyed, blue-veined, purple-headed, custard-chucking, salty yogurt slinger.

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

Something that geeks and the Wapanese do when they watch anime or run Linux on their computer.