Towards the end of Overdressed, Cline introduced her ideal, a Brooklyn woman named SKB, who, since 2008 has make all of her own clothes—and beautifully. But as Cline is the first to note, it took Beaumont decades to perfect her craft; her example can’t be knocked off.

最后一句话，我大概知道要翻译成"她的例子是不可复制的"。但"knock off"是如何引申成"复制"的含义的呢？我在词典里没查到相关的含义。

求高人解惑。