The act of ejaculating so voluminously into your partner's mouth that his/her cheeks inflate in the manner of a famous American jazz trumpeter.

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 a man squirts his baby yogurt into the mouth while being blown like a trumpet.