Disrespectful people...

Why do some people just choose to be disrespectful to you? I'm pretty extroverted and easy to get along with, and have good confidence... Most people like me and I don't feel awkward in most socia situations. But there are these couple people who treat me like I am completely stupid and don't even have anything to offer in a conversation. I think the only reason it bothers me is because I used to feel very awkward in my own body and was the "ugly duckling" all through grade school, and when I'm around these certain people I forget who I've grown up into and feel like I'm back in gradeschool. One of these people is a young male friend of my bf's, and always does little disrespectful things like put his finger in my face, stand with his butt in my fave when I'm sitting, and generally ignore me. The other is a woman that lives above me... My boyfriend does not like her either. We were just at a house party together and the only thing she said to me all night was to ask me to get her a wine opener so her and her friends could drink, and I had to go inside and upstairs to get it And she was the hostess!!! What do you do when people treat you this way? I'm sure its normal, but its so touchy for me because I am so respectful to everyone else, why is it so hard for them?