been ko'd once, fell unconscious once grappling and had one concusion.
ko was from a kick to the head, surprisingly didn't hurt. i remember looking at the guy during our sparring practice and then the next thing i remember is him leaning over me and saying "are you ok? are you ok? i'm so sorry" and slowly coming to with a warm fuzzy feeling. the room was turing a bit and eventually evened out.
being choked out was just plain weird. actually, it wasn't from a choke. i normally tap if i'm in any danger. i was in side mount but the guy had his arm wrapped around my head and a lot of pressure on the back of my neck. i remember my vision turning really foggy, sort of whiteish/grey, i think i tried to tap at that point but then things just went black. woke up not too long after and things were pretty normal.
concusion sucked most of all. to this day i can't remember my day at school at all. before or after. my friends and i were horsing around in the gym and i fell off a mat about 8 ft. head first into the floor. (4 ft high mat that i was standing on that was knocked out from under me). didn't know where my locker was, where the cafeteria was, nothing. luckily my friend was there who had a locker next to mine and i followed him back. even more lucky was that i didn't use a lock that day because i completely forgot my combo. had to "lose" my lock and get a new one. the only thing i remember from that day was following my friend to my locker and then following him to the cafeteria to eat. fucking scary day! miraculously, no bruise, no bump, no headache, no sleepiness. rock head? i don't know.