fag tag
n.— «Fag Tag is about getting together all of your friends—gay, lesbian, straight and all in between—and partying outside of the usual limited choices. Each month a different, traditionally straight, venue is chosen to be Fag Tagged and the word is spread among friends to come and party the night way.» —Fag Tag (Sydney, Australia) Nov. 11, 2004. (source: Double-Tongued Dictionary)
I have no documentation to back this up, it’s from my past.
“Fag tag” was what we called the loop on the back of oxford cotton shirts when I was in Jr. High (1967-1968). The “game” was to say that and pull the tag off of the person’s shirt without ripping the shirt. People collected them. Usually done to members of the opposite sex.