Someone who is all nice and shit, then u gat to really know her, and start thinking about bringing a shotgun to school to stop her ass from talking!!!

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

when your penis becomes erect. pretty much when you get a boner.