粵典 (words.hk)香港短語
比喻為一啲好明顯、係人都知嘅嘢；攞嚟窒人講廢話 ('mums are women', i.e. something trivially true, something everybody knows; used to imply satirically that someone is stating the painfully obvious)
語句用例
鬼唔知你阿媽係女人！
gwai2 m4 zi1 nei5 aa3 maa1 hai6 neoi5 jan2!
Oh, come on, who doesn't know that? (literally 'Ghosts don't know your mum is a woman!')