Yeah, but I'll bet they are...
Sure about what?
Based on my own adventures and misadventures at that age, I suspect that many of them aren't actually sure of anything. You're young and attractive and the world is full of possibilities and there are many things you're interested in or curious about, and you're excited to experience as much of it as you can. And some of the things that seemed interesting when you were reading about them or saw them in a movie turn out to be not quite what you were expecting.
-k