A maneuver usually pulled off in a busy nightclub, lounge or bar whereas a male rubs his Junk on the booty (behind, butt, cakes, etc.) of an unsuspecting target, (usually female) as he passes behind her on the way to his destination. Reaching this destination is not the aim of the maneuver, solely the excuse for it. The sketchiness factor falls if said gentlemen uses a diffusing statement such as "pardon me" or "it's so crowded in here" as he passes. However, this move is not to be used by an amateur as it is easily confused with sexual assault.
Vic: This bar is great, I just did a junkrub on that hot girl over there
Raj: Dude, I think she caught you
Vic: How do you mean?
Raj: She's looking over here at you disgusted
Vic: Who me? No.