I got in a few when I was a young'un. One of them was with a friend who took karate so I got my ass handed to me. XD

More recently, I got in a one-way sort of one with a former coworker. We used to slapbox during our breaks(extremely professional work environment ). One day, he had me kinda pinned and he just kept slapping with both hands. I couldn't get out and it was pissing me off. I eventually twisted around and swung at him. Except my fist was closed. :x No retaliation from him and I think we went right back to slapboxing the next day without any other incidents. :x

My sister is much more aggressive and occasionally she'll start swinging if I just mock her or something. :x Usually it's just one punch that I'll just avoid or deflect and that'll be the end of it. Sometimes I'll have to make her chase me around until she wears herself out(that or restrain her but that's no fun XD).