An all guy sleep over/slumber party.
Used in place of sleep over/slumber party to make the night ahead sound less gay and more of a manly thing to do.
p1: Hey, you coming to my all guy sleep over tonight?
p2: Don't you mean man over?
p1: Of course, what am I like?
Like a sleep over, but more manly. Usually it's when it consists of mostly dudes, and in order to not sound like a bunch of fudge packing faggots, the term "Man Over" is used.
Billy: Yo, man.
Billy: We deserve a man over Saturday night.