I've never taken any classes in an actual style; I took a general 'Martial Arts' PE course at my college, taught by a nice, 50-something man named Mr. Peck. We learned very basic versions of American boxing techniques, karate, judo throws, Filipino knife-fighting, and some strange arm binds and choke holds the origin of which I don't recall. I've also taken about a year of fencing. And way back in eighth grade my friend David taught me that nifty arm trick that you do when someone grabs your wrist, so that you twist around their hold and grab them.
I have no belts or anything, and I know I wouldn't necessarily win a fight if someone attacked me, but the knife-fighting techniques, combined with fencing, incline me to want to learn more styles that keep distance. I didn't really like judo (and I've forgotten how to exert my leverage with any real effect).
Two of my gamer friends from back home were black belts in karate or tae kwon do (I can't really tell them apart). One night two or three years ago, we were discussing grappling in D&D, and my friend Chris asks me to 'attack him.' I know what's coming, so we go to a nice open space in the living room, and I just go to grab his left wrist and punch his face. He does something I can't even follow, moves inside my reach, knocks me off balance, pins my arm, and lays his arm across my throat as we fall to the ground. The man weighs 300 pounds, so even if I weren't being choked, I couldn't have gotten out from under him.
A few months later, I happened to have a yard stick, and I was playing around with it like it was a saber. I asked Chris to come at me. He wasn't quite sure how to deal with a long weapon, since I'm sure his training would have focused on knives instead of swords. I lunged in and cut at his forearm. He tried to move in to wrench the sword from my grip, but I had about five feet of distance from him once I came out of the lunge, so he basically had to run across the line of my blade. Chris was smart, though, and he just pushed the yardstick 'sword' out of the way with one arm, so that he was getting cut instead of impaled. Then he pulled the stick out of my hand and tossed it away. I tried to run to get it, and he got me in a chokehold from behind and lifted me off the ground. I flailed for a few seconds, and then he let me go.
Anyhoo, martial arts is fun.