Don't overestimate your ability! How can you move this chair on your own?
Cantonese
阿松咁嘅尊容都学人走去做男花，好心佢自量吓啦。
阿松咁嘅尊容都學人走去做男花，好心佢自量吓啦。
A-chung looks like that but still tried to become a "male flower". He'd better know his place.
Examples (Wiktionary)
Mandarin
世上最可笑的是那些“知识里手”，有了道听涂说的一知半解，便自封为“天下第一”，适足见其不自量而已。
世上最可笑的是那些“知識裏手”，有了道聽塗説的一知半解，便自封為“天下第一”，適足見其不自量而已。
shì shàng zuì kě xiào de shì nà xiē “ zhī shi lǐ shǒu ” ， yǒu le dào tīng tú shuō de yī zhī bàn jiě ， biàn zì fēng wéi “ tiān xià dì yī ” ， shì zú jiàn qí bù zì liàng ér yǐ ．
The most ridiculous person in the world is the “know all” who picks up a smattering of hearsay knowledge and proclaims themselves “the world's Number One authority”; this merely shows that they have not taken a proper measure of themselves.