When you want to go out with a stranger for the first time but you are scared he could be a murderer so you bring your girlfriend and askthe guy to bring a guy for her so the chances of being killed lower
“Hey do you wanna go on a two man Saturday I’m scared to meet this man”
When yourself and a partner urinate into your respective cups, switch cups, cheers one another and then proceed to drink one another's hot piss for sexual gratification.
Sally and I felt like getting real greasy last night so we emptied our big gulps in the parking lot and decided to have a two-man tea party right there in the car.
when at a party/school disco, two male teenage(often univited friends (best mates and loners) who arent getting into the party and generally have distain for the music played or hosts of the party, often by shouting "two man mosh pit!", start moshing and jumping into eachother violently for a brief period startling the people sitting on sofas singing to girls aloud.
"Hey Ed, why did we go to this girls party. The music sucks"