this boy will play with your heart and flirt and make you think that your friends but the second you do something to piss him off he goes and whines about it to his parents who then contact the school

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