noun
liquid poop; intestinal fluids
Vulgar colloquial term for watery feces or the liquid that comes out with diarrhea. Used in very informal, often crude contexts.
腹を壊して、うん汁みたいなのしか出ない。
I have an upset stomach and only liquid poop comes out.
赤ちゃんのおむつからうん汁が漏れてた。
Liquid poop was leaking from the baby's diaper.
Childish or casual word for poop; うん汁 specifically emphasizes the liquid, soupy aspect.
Compound of うん (colloquial for feces, likely from baby talk or onomatopoeia) and 汁 (soup, juice). The exact origin of うん is uncertain, but it is widely used in casual and childish language.