This wasn't during sparring, but funny (now, not then). We were doing warm-ups (jumping jacks, sit ups, ect). Then we started with the stretch kicks. I was doing the front stretch kick (I was a lot more flexible then), and I kneed myself in the head/face. There's nothing worse than kneeing yourself in the head .... OUCH!
Once when we were doing sparring combos (speaking of belt injuries). We did a front snap kick and a spinning back kick. My green belt in TSD was REALLY long. I did the front snap kick and my belt came up and whacked me in my eye. Then I did the spinning back kick, and my ponytail whacked me in the other. Now I wear shorter belts, and I got my hair cut shorter LOL.
The last funny one was during sparring. I was sparring a kid (15 yo or so). We were trading some good shots. Then he stepped on my pant leg. I went to move and my pants ... umm hehehehehehe. Put it this way, my butt was showing. I yanked them up and kept going, but my instructor saw it. He said, "You can stop to fix you "sparring gear." Meaning, my pants. I was blushing the rest of the class.