不三不四 (bù sān bù sì) — dubious; shady; neither respectable nor proper (of a person's character or behavior)

Definition

Examples

• 他交了一帮不三不四的朋友，家里人都很担心。
  Tā jiāo le yì bāng bù sān bù sì de péng you, jiā lǐ rén dōu hěn dān xīn.
  He made friends with a bunch of shady people, and his family is very worried.
• 这个人不三不四的，别跟他走得太近。
  Zhè ge rén bù sān bù sì de, bié gēn tā zǒu dé tài jìn.
  This person is dubious—don't get too close to him.
• 那种不三不四的话，你最好少说。
  Nà zhǒng bù sān bù sì de huà, nǐ zuì hǎo shǎo shuō.
  You'd better stop saying that kind of inappropriate talk.