Not my worst but one of the more unusual shits I've taken. On hwy 90 between Uvalde and Brackettville '88 or '89 around 1030pm. Pulling out of Uvalde I felt some pressure but figured I could hold it off for the last hour of the drive. Nope. It started getting critical but I didn't want to pull over on the side of the road because by then it was well known that illegals were all over the place in the brush along the road. I was able to hold out long enough to reach the big double bridge that crosses the Nueces and no one could approach the truck. It has a decent size shoulder so I pull over, drp trou and squat with my back against the side of the truck for support. Dad always told me to keep a roll behind the seat just in case. And this was just the case. I finish my business and as I get back in the truck a DPS trooper pulls up. He asks why I was stopped on the bridge. I explained my reasoning and offered to show him the evidence. He said that's ok, just be safe getting home. After I pulled off I'm sure he could see the giant Hershey kiss looking dookie I had left on the shoulder of the bridge. Since I had thrown my tp over the guardrail I was laughing that he might think I hadn't wiped!
Worst was sitting on the beach in Puerto Peñasco back in the 90s before it had become the tourist town it is now. I had a huge shrimp cocktail for lunch. Later on sitting on the beach molten lava began rumbling. No porta potties in sight. I penguin walked out into the water where it was almost chest high. Removed my trunks and proceeded to make my own shark repellent. Swam away from the cloud to clean up in clearer water. Slipped my trunks back on and went back to my towel on the sand.