I was wondering if I pooped in a bucket on my own property and someone came along and took it without permission would that be theft? I mean it’s poop, so once it leaves the body, does it not count as “property” anymore? 

Scenarios:

1) You poop somewhere away from home and someone collects it after you leave:

Not theft. You left it behind it can't reasonably be expected you would be returning for it.

2) You poop at home and have a septic system

Theft and potentially destruction of property- if they dig up your septic tank to get to your poop that can only be considered criminal.

3) You poop at home and leave an unflushed turd and they steal it

This is a grey area. A grey/brown area. I would say in this case not theft, unless you ask them specifically to not take your poop with them. Again, it can be reasonably expected that you meant to throw away your poop.

4) You poop at home and someone is waiting in the sewer below your house to steal it.

Not theft. It can reasonably be expected you were throwing it away and the poop is free-game. The city's sewage department might get them for trespassing though.

5) You go to the doctors for surgery and while there a nurse reaches up your ass and grabs a turd from your innards and flees holding it. Perhaps you're under general anesthetic when this happens, or perhaps you have a nurse that really pushes the boundaries.

I think in this case it qualifies as assault, medical malpractice and grand-theft turd.

Thanks for reading. Have a poopy day.