Biology question

Why does a sphincter have such a messed up sense of geography?

Or a sense of geography at all, for that matter?

Because inevitably, when you're two or three blocks away from home, your sphincter says, "Oh good, we're home" and starts to relax, even though every other fibre of your being is screaming: "NOT YET NOT YET NOT YET NOT YET!"

Someone needs to invent a sphincter GPS. In this case, though, it would be a "geographical poo synchronizer."