brag unblushingly 大言不惭

“大言不惭”，汉语成语，意思是说大话而不觉得难为情，可以翻译为“brag unblushingly，boast shamelessly，或be insolent enough to say something”。

例句：

他会大言不惭地吹嘘自己的能力。

He could become ungraciously immodest about his own capacities.