马尾穿豆腐，提不起来
mǎ​wěi​chuān​dòu​fu, tí​bu​qǐ​lai

fragile

马尾穿豆腐，提不起来 (馬尾穿豆腐，提不起來) mǎ​wěi​chuān​dòu​fu, tí​bu​qǐ​lai
fragile
literally like tofu strung on a horsetail which is impossible to lift; used to describe a situation or object too weak or poorly constructed to be supported
unmentionable
figuratively used to say 'don't mention it' or 'let's not talk about this', based on a pun on the word 'ti' (meaning both to lift and to mention)

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