Slammed my pinkie finger in a big heavy house door when I was 9 or 10 and ripped the fingernail off.
Right at the start of the summer, meaning I couldn't go swimming on our yearly holiday.

Fast forward a year and I bust my index finger by knocking a rock onto it and splitting it, meaning I couldn't go swimming yet again. :-(
( Spider Fucking Riviera got stiches for a knife wound for the first time, Fri 7 Jan 2011, 4:43, archived)