The one where I was an honest-to-god stalker, but just for an hour.
When I was 13 my friend Gabe and I (Gabe is a girl) followed a boy (maybe 15) through Manhattan because we thought he was cute. We spotted him on the bus, though I can't imagine why we were on the bus since she lived half a block from school. Maybe we'd gone somewhere? Maybe we were going to my apartment? Anyway, we got off the bus when he did and followed him to a private school where he picked up a little girl (presumably his sister). Then we RAN to catch the bus he boarded, making ourselves extremely obvious. Then we got off at their stop. When he got to his building, he picked up the little girl, turned, and waved at us.