A "two man" refers to when one of your friends wants to hang out with a woman, but the woman insists on bringing her friend. You then tag along with your friend to help prevent a potential cock block.
Hey dude, Lucy's bringing her friend with her to the movies. Do you want to make this a two man?
when a dude and a girllink up and he brings one of his mates and she brings one of her mates for him.
"yoo so yk how we r gonna meet on friday? imma bring one of my homegirls along do u got any cute mates for her so we could do a two man?"
"yeah ok bet i know a guy ill let him know now"