promising easily/stating a fact without prove or thought
Definitions (粵典–words.hk)
形容詞
唔諗清楚自己做唔做到就應承;下巴輕輕 making promises lightly without thinking through the consequences; literally: mouth loud
你咪應承得咁口響,到時你做唔晒啲嘢,老細實鬧你。
你咪应承得咁口响,到时你做唔晒啲嘢,老细实闹你。
nei5 mai5 jing1 sing4 dak1 gam3 hau2 hoeng2, dou3 si4 nei5 zou6 m4 saai3 di1 je5, lou5 sai3 sat6 naau6 nei5. Don't promise what you cannot deliver. If you can't finish all the tasks when the time comes, you will be scolded by the boss.
Definitions (Wiktionary)
adj, Cantonese
making irresponsible remarks without thinking through