The Ambiguous English Language

What happens when straight guys don't know the use of the world "girlfriend" as meaning platonic female friends:

P.A., dropping me and two other girls off at hair and makeup, to the hair and makeup crew: "Harper's girlfriend (pointing at one of the other girls), Harper's girlfriend (pointing at me), Harper's girlfriend (pointing at the third girl)."

 

Crew guy: ".....He gets three girlfriends?" 

 

P.A., as he walks away: "Yeah, he's busy!"

 

Makeup girl, smiling, to crew guy: "Harper's a girl."

 

Crew guy, mouth open, clearly envisioning things: "..........Lucky girl."