http://www.odps.org/glossword/index.php?a=term&d=8&t=8609
Mary
n.
A nick name for another homosexual.
Synonym: Alice May; Bess; Bessie; Betty [known SF72]; Blanche; Brenda; Clarisse; Core; Emma; Emmy; Gussie; Maisis; Maria Marjorine; Martha; Mintie; molly Ravonia; Rose [known Southwest, mid 60s]; Sally [mid 60s]
A male homosexual who takes the passive, feminine role.
A lesbian.
Ah... well, you learn something new every day. ;-)