When you take a poo then 5 minutes later you have to take another one.

The experience of thinking you have had the same poop, on a previous occasion.

The additional call of nature - very similar to the first - that lures you back into the toilet, even though you're pretty sure you've just moved your bowels satisfactorily.

When you take a shit in succession of the same size, quantity, shape, and consistency.

When you take a dump and it feels the same, looks the same, smells the same.

De ja vu while sitting on the toilet.

When you are so drunk that you're very well into a blackout state and you make it home to take a massive poop on the toilet. The poop drains so much energy out of you that you pass out on the toilet before flushing. When you wake up in the morning you see the poop, but can't actually remember ever taking one and are still able to recognize it as your own.