To elaborate further, your butthole is what’s called a “sphincter”, which is a ring-shaped muscle. You’ve got a few in your body, and they mostly keep fluids where they’re supposed to be. As long as you don’t damage the muscle, you don’t have problems.

Now, opiates on the other hand, are a different story and will absolutely fuck up your poop. I worked at a junkie hotel once and found a turd the size of my foot in the stairway once.