So you're about to have an attack of diarrhea. You're in your car and there's no way you're going to make it home. No problem!!!! Get out your iPod and google Imodium.com. Enter your zip code into their handy dandy "bathroom finder" -- yes, you read that right -- and you can find out where the closest toilets are located before your Corinthian leather seats are history.
Here's proof I'm not making this up:
Some day there's gonna be an app for this.
P.S. Most of the bathrooms I found were at Starbucks. Duh.