爆大冷 [－－－]

Jyutping baau3 daai6 laang5
Pinyin bào dà lěng

Definitions (CC-CANTO)
  1. a totally unexpected result in a match with the most unlikely winner going through [written and colloquial]
Definitions (粵典–words.hk)
  1. 動詞
    發生​一​啲​極之​出人意表​嘅​事​；​非常​冷門​、​勝算​唔​高​嘅​選​手​或者​馬​贏​咗​賽事
    a completely unexpected result in a race or match, a big "upset".
  2. 近義詞
    爆冷