A fork of Rural Dictionary
When you do something amazing that would normally take more than 4-5 people.
In Modern Warfare 2: Guy 1: "Hey you just killed the entire enemy team in Ground War!" Guy 2: "I know, I'm a one man gangbang!"
When one man starts a gangbang and no one taps him out because he's just that good.
Amanda: Hey look at Billy go Sarah: Yea, he's a regular one man gangbang Or Amanda: hey Sarah how's your ass feeling today? Sarah: Surprisingly not bad after having Billy, The One Man Gangbang. He's gentle!