It's annoying. Doesn't really tickle, maybe a bit, but in this unpleasant way. I could handle a couple seconds long teasing, like feather on your nose, but that's it. Anything beyond that is just annoying as hell.
I have a friend who seems like she can't stand having her feet tickled. Any touch would make her squeal (barely even laugh) and move her feet away instantly. So I guess she falls under that category, or at least it's the closest I'd see it.