I have a half-marathon this Sunday. I already lost the requisite toenail and the race hasn't even started!
Seriously...I must have somehow injured my toe. When I went to apply varnish (I always keep the toes manicured. I can't keep my fingernails from breaking to save my life), toe #2 on the right decided that it didn't need the toenail anymore. And this injury must have occurred quite a while ago, because the next toenail was already halfway grown out. How I didn't notice this is beyond me.