A male friend with whom another person spends large amounts of time. Describing someone as your "manpanion" does not imply that any sort of sexual activity takes place.
A man who is your companion.
Girl: You spend so much time with Frank, its like he's your boyfriend Guy: Relax baby, we just enjoy playing video games. He's my manpanion.
A combination of the words "man" and "companions", this term is used to describe a straight but less romanticbromance. Also used to describe (straight) men who do things together. A comical connotation is recommended.
Girl 1: Did they go to the storetogether?
Girl 2: Yeah. They're manpanions.
"Last December, my male companion (can I say manpanion?) took me to a
performance of the New York City Ballet's "The Nutcracker "as an early
Christmas gift. I had a great time, too!"
-- heard at a watercooler in Brooklyn on January 3, 2012