A proverb meaning there's no medicine for stupidity—i.e., there's little that can be done to change foolish people.
何度注意しても同じことをする彼には本当にアホにつける薬なしだ。
No matter how many times I warn him, he does the same thing—there really is no cure for fools.
そんな簡単なミスを繰り返すなんて、アホにつける薬なしだね。
To repeat such a simple mistake—there's no cure for stupidity, huh.
彼らが聞く耳を持たないなら、もうアホにつける薬なしだと諦めるしかない。
If they won't listen, we can only give up and say there's no cure for fools.