You know... I don't know. But, when I read your title... I honestly couldn't figure out if you meant actual poo, or pooh - as in Winnie-the-Pooh! (Yes, my inner brain is apparently 5-years old).

When I read the first sentence (quoted above) - I actually burst out laughing out loud.

Maybe it's just a stress reaction (laughing) to something that is a little uncomfortable to talk about? I mean, because clearly there's not really anything funny about it in real life. Not like people are banging on the bathroom door saying, "Hey? What's with all the laughing in there? You're not taking a poop without me, are you?! I can hear you!!!!"