自作聪明 (zì zuò cōng míng) | Meaning: (idiom) to think oneself clever | Chinese Idiom with Pinyin & Origin

to display one's slight skill before an expert (idiom)班门弄斧Bān mén nòng fǔ

to believe oneself infallible (idiom) · to be opinionated自以为是zì yǐ wéi shì

to put on an act故作姿态gù zuò zī tài

to show off one's cleverness · (of sb who has received beneficial treatment) to profess to have been hard done by卖乖mài guāi

(idiom) to think oneself clever