Poop Machine Meaning

(idiomatic, pejorative or humorous) An animal whose defecation inconveniences humans.

Example: 2012, J. A. Pitts, Forged in Fire, Tor Books (2012), ISBN 9780765324696, page 147:
  […] 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."
2000, Gerry Buccis & Barbara Somerville, Training Your Pet Rat, Barron's Educational Series (2000), ISBN 9780764112089, page 85:
  Then, there's scooping the poop. Rats are real little poop machines.