To have anal sex while she is stuck in the backdoors of a van while some one else drives in the desert. Once you ejaculate, go and jump in to a moving dune buggy and drive off. Strap-ons are acceptable if the 2 are lesbian.

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