挖空心思

wā kōng xīn sī tì zì jǐ biàn hù

挖空心思替自己辩护

rack one's brains trying to justify oneself

wā kōng xīn sī wèi tā zì jǐ biàn jiě

挖空心思为他自己辩解

make every excuse to justify himself

wā kōng xīn sī qù sǔn rén lì jǐ

挖空心思去损人利己

cudgel one's brains to benefit oneself at the expense of others

tā wā kōng xīn sī fǎn ér bǎ shì qing quán pán nòng zāo le

他挖空心思反而把事情全盘弄糟了。

He contrived to make a mess of the whole thing.