愚蠢 + 的 + Noun
The adjective 愚蠢 (yúchǔn) means "foolish," "stupid," or "idiotic" and is a strong term used to describe a lack of intelligence or poor judgment. It is more emphatic than 笨 (dumb) and can be considered harsh in direct conversation. Use 愚蠢 to describe clearly unwise actions, decisions, or people.
那是一个愚蠢的决定,大家都反对。
Nà shì yí gè yúchǔn de juédìng, dàjiā dōu fǎnduì.
That was a foolish decision, and everyone opposed it.
不要做这么愚蠢的事,会后悔的。
Búyào zuò zhème yúchǔn de shì, huì hòuhuǐ de.
Don't do something so foolish; you'll regret it.
他意识到自己犯了一个愚蠢的错误。
Tā yìshí dào zìjǐ fàn le yí gè yúchǔn de cuòwù.
He realized that he had made a foolish mistake.