What's P'shat?

I consider myself relatively bright (others may disagree) but there a few things I don't understand. Yesterday, as I was walking to work, I saw two phenomenon that I didn't get. First, a guy wearing baggy sweatpants, one leg down and one pushed up to the knee. What's up with that?

Second, a man appearing to be in his mid-sixties, bald, wearing what's left of his white hair pulled back in a long pony tail. I see a lot of that. I never got it. I still don't.