愚钝

bié wèi tā làng fèi nǐ de shí jiān tā nǎo zi yú dùn

别为他浪费你的时间，他脑子愚钝。

Don't waste your time with him. He's a space case.

zhǐ gōng zuò bù yú lè shǐ rén yú dùn

只工作不娱乐使人愚钝。

All work and no play makes Jack a dull boy.