This thread - is absurd.
The military is full of nick-names.
A "Monterey Mary" is a term that is used in the military to indicate a graduate from the Defence Language Institutel in Monterey California. They are language specialists. All branches are trained there, and some foreign services. It is NOT a playground. No kids here...these are very much adults in every sense.
They use "Monterey Mary" to describe themselves. Not effeminate. Not a putdown. Not a phobia. There is nothing "gay" about the term (and the woman - on occasion - do wear combat boots - and many are mothers - and their daughter are proud of them) It is not a slur.
I has been my honor to work with and have extended friendships with a few graduates of the Insitute (One has the ability (incredible to me) to listen to ANY language sound, note it in a form of shorthand and precisely repeat back the exact phrase. The skill is used to clarify particular words, expressions, names in interrogation.
They are HIGHLY respected and have been deployed to some of the vilest/nastiest places on the face of the earth. They have AMAZING skills.