shit strainer
A person lacking any usefulness whatsoever except consuming food and producing shit.
Chase is 35 years old hasn't worked a job in his whole life, sufficing only on video games and free loaded food from his parents as he continues to occupy their basement. Chase is one of the most useless shit strainers you'll ever meet.
Shit through a strainer
An extremely runny, liquidy shit or series of shits that could completely pass through a strainer; diarrhea.
I could eat that all day, but does it ever make me shit through a strainer.