Barrel bop

Derived from the practice in which a sailor is placed in an empty barrel full of glory holes and his sailor mates use said glory holes to spaff on him

"You and your mates are so gay I bet you barrel bop each other at any given opporunity!"

"Yeah she looks like a right slag I bet she loves a barrel bop"

"Yeah he's a bit film actors isn't he I reckon he wants a go in the barrel for a quick bopping"