Are you nipples super sensitive? You are not alone. Below is some advice given to a woman who orgasms from nipple stimulation.

I’d say there are a couple of things at work in your case. One is that you’re reacting to Oxytocin, which is a hormone related to breast feeding, bonding and uterine contractions. It’s secreted when someone sucks on your nipples, as well as when you have an orgasm, and can make you feel all sexed up and happy. I’m still amazed that someone hasn’t figured out how to extract it, cut it with speed and sell it at raves.

Also, people can do pretty much anything they to want if they put their minds to it. If you wanted to have an orgasm while sitting in an economics seminar, for example, you could. The brain is our biggest sex organ, so whatever you latch onto up there can get you excellent results down there. In fact, I’ve taught myself to have an orgasm with zero physical stimulation. Hands free. I just get a filth fest going on in my brain, concentrate real hard, and there she blows. I’m confident that with a little hard work and a good lesbian gang bang fantasy or two, you could make your knobs go to 11 as well. (Source)