noun, noun or participle which takes 'suru', intransitive verb
Childish or informal word for feces. Used by children or in casual, affectionate contexts. Can also be used as a suru-verb meaning 'to poop'.
犬が公園でうんこをした。
The dog pooped in the park.
子どもが「うんこ！」と言って笑った。
The child said 'poop!' and laughed.
noun
Slang extension: used to describe something of very poor quality, worthless, or contemptible. Strongly informal.
このゲームはうんこだ。
This game is crap.
そんなうんこなアイデアはやめろ。
Stop that crappy idea.