The word "破绽" (pò zhàn) itself refers to a defect, flaw, or vulnerability in something. So, when someone says "卖个破绽," they are essentially suggesting that someone is exposing a flaw or weakness in a situation or in someone's argument.
将“破绽"翻译成英文 . flaw, hole or tear in cloth, mistake or gap in a speech or theory (idiom)是“破绽"到 英文 的最佳翻译。 译文示例:米勒的小丘露出破绽,影响所及,他们的额菲尔士峰也倒塌了。 ↔ Miller’s molehill was flawed, and with its demise their Mount Everest collapsed.
Unfortunately, I found that your work had a tiny flaw. 很不幸; The flaw in this vase makes it less valuable. 这个花瓶因为有点缺陷,不那么值钱了。 I can't find a flaw in his argument. 在他的论点中,我找不到任何破绽。 Your argument has a fatal flaw. 你的论点有一个致命的错误。 …