Someone who spazzes over a girly or girl-like subject, such as fashion or boys. Girlspazzing can occur in boys, but is mainly referring to girls. See fangirl
Girl 1: Ohmehgawd, you have science second period, right?
Girl 2: Yeah, why?
Girl 1: That superhot guy Ben is in that class, he's so cute!
Girl 2: Girl, please. Stop girlspazzing and get over that jerk.