Then by extension, anything designed for the female anatomy would be crossdressing, thus, if I don't wear a bra with my skirt would taht be crossdressing? As someone stated before, a jockstrap would be about the only piece of clothing that would be specifically for a male. A bra (with a few exception of gynecomastia) would be the only piece specifically for a female.
I move we don't call GG's who wear male (ugh did I just classify a genderspecific clothing) clothing crossdressers if they don't do the same to us.