'Streetcars' they are and calling them 'trains' marks one as not yet being a fully naturalized San Franciscan.
When I was in high school in the late '50's we had a guy who forged car tickets and after they were crumpled up, you couldn't tell the difference.
I bought them from Len, the blind vendor at Forest Hill Station.
Apropos of 'nipping' a ride on the old ellipse fenders, years ago I was waiting on the outbound platform at Forest Hill Station when a PCC car arrived from Castro St.and when the car came to a full stop, a teenager climbed off the back of it. He had put a 2' length of broomstick through the trolley wire winder, hooked his toes on about a 3" ledge that runs along the back of the car, and ridden through Twin Peaks Tunnel. I still get the willies when I think about it.
Incidentally, Muni defines 'inbound' as heading toward a bridge. The #30 and #24, for instance, are inbound when heading north, even though they are going away from Downtown.