三九四零五二 [－－－－－－]

Jyutping saam1 gau2 sei3 ling4 ng5 ji6
Pinyin sān jiǔ sì líng wǔ èr

Definitions (CC-CANTO)
  1. six numbers pronounced with the first tone to the sixth tone respectively in Cantonese: 3, 9, 4, 0, 5, 2
Definitions (Wiktionary)
  1. phrase, Cantonese
    A phrase used to memorise the six tones in Cantonese