To be young in NY. It is often said, though I don't know who first coined the phrase, that New York is only for "The very rich, the very poor and the very young." It's not true of course but I was quoted this by a long-time resident when I first arrived. He asserted that when I fell between these three groups I should leave.
Day 4 - A young couple kissing on the uptown 3 train, just after 72nd street.