If you learn anything from road trips, it's to avoid food that looks suspicious. In fact, avoid anything that doesn't look right. Just get back in the car and go.
Patrick wrote about a guy who started a freaking off-road chase to stop the highway patrol from pulling him over and preventing him from getting to a toilet in time to relieve himself.
Combo1234 did a not-so-subtle job of telling us about the unfortunate incident he faced and why the printed road map should never die:
Pepto Bismol is a fantastic idea, but lets be realistic, once you're past the point of no return, chugging the entire bottle won't help. What you really need to have on hand to protect yourself, and more importantly your vehicle, when just such an emergency arises is a nice, large, old style road atlas in the sleeve behind your seat. Not for the wonderful cartography that's inside, but to act as a large 1/2" thick virtually impenetrable buffer between your sphincter and the cloth / leather on your seats. Once the point of no return has been reached, place the atlas under your bum, and cut it loose. Your underwear and pants will get destroyed, but the mighty atlas will save your car.
Trust me, I know from experience dude.
Look at it this way: Rand McNallay has nothing on Google in this department.