Someone I know was so desperate to go when they were out one time that they dropped a log on a street corner...then used THEIR OWN (probably sweaty) SOCK to finish the job *shudders*.
As for me, I always check there's some trusty toilet paper around when nature calls. If you have enough fibre in your diet, I've heard that you can get such a flawless evacuation that you don't even NEED toilet paper some of the time. Now that's progress!