The sharp serrated opening at the top of a bottle of COVID sanitizing wipes that resembles a butthole and can be dangerous to reload due to the likelihood of one’s finger becoming trapped and/or cut.

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