|1.||random hook-up buddies|
Much like a friend with benefits, a random hook-up buddy is someone you're not actually in a relationship with but still get busy with.
Unlike a friend with benefits however, random hook-up buddies hook up on less frequent, more random (hence the name) intervals.
"Mark and Brooke must be random hook-up buddies. The two or three times a month they see each other they always get busy."