The last girl a guy dates before coming out of the closet.
Particularly applicable when this has happened many times to the same girl; she is the train men ride from their closet in Trenton to the out and proud parades of Philly.
A doubly unwitting beard
A special kind of fag hag
Don't mess around on that SEPTA, she'll be the last ride you take.
Turn them once: shame on you. Turn them twice: you are the SEPTA.
(To a gay man): Don't get your hopes up just 'cause I'm riding the SEPTA.