Is it normal that touching freaks me out?

First of all, there is no abuse, sexual or otherwise, in my past. It's not a result of any beliefs of mine, religious or otherwise. I'm a people-person, very extroverted and social. I like hugging close friends.. but well.
I'm also very jumpy. My classmates have of course noticed this, and everyone seems to find it extremely amusing how any sudden movement or noise-often even if i know it's coming-makes me jump two metres high. Usually it doesn't bug me, but sometimes people go too far.

I get panicky and distressed when people poke my waist. Or anyplace else too, for that matter, if they don't stop after one or two rounds of playing with my reflexes. It makes me feel like i'm not in control of my own body, and i will be shaky for hours. Also, i'm unable of wearing clothes that would make me feel pretty, because that does seem to provoke even more poking and fiddling in certain people. It's always playful, i think, yet it makes me feel horrible. And the most problematic person won't actually listen to 'no's unless it comes with an insult. I don't do insults. And i'm not comfortable with letting people touch my hair, or back or especially waist, unless they're really close friends. I have a few friends like that, both male and female. Other than from those people, it just doesn't feel good, no matter how innocent the intention. And I feel like i'm making a big fuss about nothing. Please someone explain this to me?