Dunking your whole head in the holy water font at a Catholic church because you were in a hurry to confess to performing oral sex and you wanted to get that taste out of your mouth first, or because you didn't have time to brush your teeth after eating the nasty garlic chicken at that Chinese place up the street and you didn't want the Body of Christ to taste like nasty garlic chicken.

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