A Minecraft mod developed for my 11 year old daughter, who takes credit for the idea ;)
So far, adds "Poop" functionality to Minecraft 1.7.10. Requires Forge 10.13.4.1448.
Eating causes Poop to fill up and is displayed on an on screen bar. When full of Poop, player slows down and is also unable to eat additional food. Poop is removed by crafting and using a Toilet. Toilets are crafted with 8 wooden planks surrounding a water bucket:
P P P P W P P P P
Where (P) is a wooden plank and (W) is a water bucket.
When toilet block is "activated", a poop item is produced.
Poop will (eventually) be able to be smelted to create fertilizer which can then be used to help grow crops similar to bone meal.