I had recently gotten surgery to fix an ingrown toenail. Then, during sparring, my brother did this kind of spinning sweeping heel kick thingy, and he ended up tearing my toenail half off. Two years and three surgeries later, it's still causing me problems. It's only just starting to heal after I went to an acupuncturist. But until it does, I won't be doing any roundhouse kicks with my right foot.