As I was walking to the bus after work today, I passed two teenage boys going the opposite way. A second later, I heard one of them ask the man walking behind me, "Hey sir, is that your girlfriend?"
"Her." Though I couldn't see the boy point to anyone, I was the only "her" in the vicinity.
"I was gonna smack her ass."
So the only reason you didn't was because you thought another guy would get pissed off at you. Lovely.
(Side note: As I was deciding whether to pass on the street side of them or between the kid and a bush, I thought, "They're just kids. Stop worrying so much." STOP PROVING MY POINT.)