Yes, i have.
And i have no shame in saying i fight dirty. I take cheap shots. I dont care what people say. As far as im concerned, if someone attacks me, they cease being a human and simply become another physical body trying to hurt me, and after whats happened to me in the past, i wont take it. Im not the biggest guy, and ive discovered following the "Rules" of fights, only puts me at a disadvantage, especially with someone bigger than me. Thats when i decided there are no rules.
Since past events, ive actually been taking hand to hand fighting techniques here taught by a russian ex-spetznaz. Ive only been doing it for 3 months, and its hard, brutal tuff, but i feel good about myself for learning it.