打沒頭壇 [－没头坛]

Jyutping daa2 mut6 tau4 taan4
Pinyin dǎ mò tóu tán

Definitions (Wiktionary)
  1. verb
    to dive headfirst into water; to swim with your head underwater
    (syn.) 打猛子, 沉沬, 扎猛子