Edit: wow, this blew up (no pun intended) so I guess I'll share my horrific story from last night.
I had just finished dinner at a restaurant with my boyfriend and his family. Food was great, everything was fine (including my stomach). We all say goodbye and I get into my car and start driving home (about 20 minutes away). My stomach starts to gurgle and I let out a fart. I feel some relief and figure the feeling will pass and I can make it home. But oh god, the feeling does not pass. I just make it on the highway and realize there's no fucking way I'm making it home without stopping. I drive about 3 miles and get off at an exit, frantically looking for a gas station or... Well anything at this point. All around me are business buildings... All closed. It's getting worse and I'm clenching my butt as best I can. I figure if I can find a semi secluded dark parking lot, I'll just let loose there. I decide this at a light that took a god damn eternity. I'm waiting, and shaking, and sweating, and the light isn't changing. Then it changes... And then it happens. The poop is released into a brand new pair of underwear and my favorite jeans. I cannot even explain the warm, mushy feeling. I pull over to the first parking lot I see with no cars. Oh great, it's a middle school. Luckily, it's mostly surrounded by trees. I pull over by the dumpster, jump out of the car, squat and realize this beast isn't done. I shit more, take off my pants and underwear and go in my glove compartment where I keep a bunch of napkins. I try to clean up as much as possible and realize my underwear is a lost cause. I'm so mortified that I forgot to put my underwear in the dumpster so I left it. On the grass. In a middle school parking lot. I always keep extra underwear in my purse, so I put them on and drove home with the windows open. I'm sorry to the person who finds my poop, underwear, and napkins covered in feces.