Being 16 is grand, but being 18 is awesome. But being 21 is even better.
I'm currently 18, and I tell you what, It is nice being 18, but then the realization hits you that you have to be responsible, and then the fun goes down the drain, well not completely.
But somethings that I can't do because I am not old enough, buy a hand gun, buy alcohol, drive for a company. So far that is all that I have found. I know this is going to sound cliched. but have fun while you can at 16, here pretty soon you'll be 18 and you'll miss being 16. I don't know how many times I was told that, and was like "yeah right," but now that I am older, every word of that advice is true.