3 sentences

1. 这种见不得人的勾当，你千万别参与。

   zhè zhǒng jiàn​bu​dé​rén de gòu​dàng, nǐ qiān​wàn bié cān​yù.

   You must not get involved in such shady business.

   Source: Dong Chinese Dictionary

2. 他们勾搭在一起，干了不少违法的勾当。

   tā​men gōu​da zài yī​qǐ, gàn le bù​shǎo wéi​fǎ de gòu​dàng.

   They teamed up and committed many illegal acts.

   Source: Dong Chinese Dictionary

3. 他因为经常干些小偷小摸的勾当被抓了。

   tā yīn​wèi jīng​cháng gàn xiē xiǎo​tōu​xiǎo​mō de gòu​dàng bèi zhuā le.

   He was arrested for frequently engaging in petty theft.

   Source: Dong Chinese Dictionary