Haven't had people honking at me while walking around, that I have noticed, but it does sound like something I could potentially be paranoid about.
Once, while waiting for a red light to cross the road, some car with a bunch of random people shouted something and laughed as they drove by. I don't know what it was about, as I had my earphones on blaring some kind of music. I just considered them to be a bunch of immature kids, and shortly after crossed the road while the green light came on.
Such things aren't really worth to think to much about. They would have done just that, regardless of who they found walking down the road.
As for the honking; if you're just walking on the sidewalk minding your own business, in most cases, it is not directed at you. If it is, it's just like with the situation I described above. Unless, of course, it happens to be someone you know.
It's still immaturity, though, as, as far as I know (don't have a drivers license), the horn should not be used unless there is a dangerous situation happening.