不三不四
bù​sān​bù​sì

dubious

  1. 不 bù adverb
    not
    Negative adverb used before verbs, adjectives, and other adverbs to indicate negation; also used as a bound-form prefix to form terms with opposite meanings
  2. 三 sān numeral
    three
    the number three; 3
  3. 不 bù adverb
    not
    Negative adverb used before verbs, adjectives, and other adverbs to indicate negation; also used as a bound-form prefix to form terms with opposite meanings
  4. 四 sì numeral
    four
    the number four; complex form used for financial purposes is 肆 sì