stupid
頭が悪いね、君。
You're stupid, you know.
ここだけの話だが、彼はだいぶ頭が悪いと思うよ。
Between you and me, I think he's pretty stupid.
ただ単に頭が悪いだけじゃねえのか~?
Could it just be that you're stupid?
— AKIRA (1988)
頭が悪いばかりか生意気だそれに恥知らずだ
Not only are you stupid, but you're also insolent—and shameless to boot.
— 大人は判ってくれない (1959)