Yeah I have. A few times. Once there was this guy who kept hanging around the park near where I lived to see me. One day he finally approached me and asked me to go out to dinner with him. I turned him down, I was only like 15 at the time and I wasn't that interested in dating. I just said "Sorry, I don't really know you to be honest. I'm not really interested." And he walked off quite sad. I never really saw him again after that.
Another time was recently. I was walking to work and this guy stops me. It was actually hilarious. He said, and no lie, this is exactly what he said "ooo damn girl, you are, like, my cup of tea! I can't just let you walk away looking so fine." I couldn't hold the laughter. I honestly couldn't. I felt so guilty for laughing. I said "I bet you say that to all the ladies." And he said "No, no, so how about it? Can I have your number?" I turned him down, telling him that I have a boyfriend. He was persistant, and asked for my number to be friends. I said no. And that was that.