不登大雅之堂 [－－－－－－]

Jyutping bat1 dang1 daai6 ngaa5 zi1 tong4
Pinyin bù dēng dà yǎ zhī táng

Definitions (CC-CEDICT)
  1. lit. not fit for elegant hall (of artwork)
  2. not presentable
  3. coarse
  4. unrefined
Definitions (Wiktionary)
  1. phrase, idiomatic
    to be unrefined or unpresentable; to be too vulgar for polite company; to not appeal to refined tastes