I did read a story following this in which a runner had a case of the - um - runs, to her embarrassment - and they came on unexpectedly and a few kms after she had passed a toilet. She managed to go in the bushes about 300 m from the finish line, and then finished, and ran straight to the loo and spent an hour there before she came out. She said it was awfully embarrassing and not something you'd reaally share with anyone ever, except for this 'news' event. Apparently it happens more often than people appreciate.