Subtle way of saying gang bang in front of the person you intend on having it with, without their prior knowledge. whether it be two or more men/women teaming up on a woman/man, or a group of friends that know they all have the easy in with a certain individual.
Originated in San Antonio, TX
Guy 1: yo I just got a text from homegirl!
Guy 2: I just got one too!
Both: GONGO BONGO!
Girl 1: Hi I'm (name goes here)
This is my friend (name goes here)
Girl 2: Hi there.
Guy: would you ladies like a drink?
Both girls aloud to eachother: Gongo Bongo!