Sloane Crosley: 'We spend our childhoods trying to grow up and our adulthoods nostalgic for our youth'

Today at breakfast I sat next to two of the most put-upon people in the world. They complained about people they knew (their friends, their family), then they moved on to people they didn't (the waitress, the hostess, the homeless in general). The proximity of our tables made it bizarrely difficult to sneak a glance at them without arousing a reaction. And judging by the casual vitriol slung at subway employees, I had a "Do you mind?" coming my way if caught.

So it wasn't until I got up to leave that I discovered I had been listening to two teenagers for the past hour. The girl, maybe 15, was dressed in a leopard-print vest with her sunglasses pushed back on her head. She gesticulated with a cherry from a virgin cocktail. The boy, 12 or 13, sat slumped in his chair with one scrawny elbow over the back, as if modelling for a magazine piece on Young Titans of Finance.

I know. I shouldn't do this. Because there's only one direction for this story to go, and that place is called Kids These Days. We all recall the feeling of dying to be older, and it's curious that no matter how you grow up, the element of adulthood all of us choose to imitate is to be "over" everything.

Drugs? Tried them. Sex? Had it. The opposite sex's behaviour? So seventh grade. Nothing betrays youth like newness. Of course, when we grow up, we put a premium on a wide-eyed wonderment of the world. We value a lack of the jaded and the bitter in each other, and do everything in our power to stave off these qualities in ourselves.

As I left the restaurant, I felt myself thinking, "Oh, these Manhattan kids!". Then it occurred to me: I don't think that's what actually bothers me about seeing kids playing at being adults. It's not that they grow up so fast. They don't. But if we spend our childhoods trying to grow up, and our adulthood nostalgic for our youth, when do we just get to be? Surely there must be an exact halfway point. I'm thinking it's 18 in the UK and 21 in America. Because you could be drinking to forget the past, or to toast the future and no one particularly cares. All that matters is that you're meant to be here.

Sloane Crosley is the author of 'How Did You Get This Number' (Portobello Books)