When a man ties a tight string around his penis and slowly moves it up and down until fully erect. Then, he unties the string and rubs it all over the head of the penis until he precums. Then, the man ties the string tightly around the bottom of the penis and masterbates slowly using his right hand and rubbing his head with the left until orgasm. He then leaves the string on for another 5 minutes or until the penis is completely numb and then takes it off and rubs the head of the penis delicately until he loses his erection.

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