poop machine

noun2

1. •
   (informal, humorous) An infant.

   • […] Never could keep friends long, so I figured if I had a sister, I'd at least have someone to be friends with, even if she was a crying poop machine for the first year." — 2012
2. •
   (humorous) An animal whose defecation inconveniences humans.

   • Then, there's scooping the poop. Rats are real little poop machines. — 2000