怎么用草船借箭这个成语 how／when to use 草船借箭 When and how do we use the idiom 草船借箭?

I know where the story comes from — 《三国演义》— and I know the meaning. But I'm still not really clear in what situation I'd say this.
It's not a 成语, actually. As a Chinese person who was born and raised in mainland China, I've never ever used it as a 成语, and I've never heard anybody use it as a 成语. When our teacher told the story of 草船借箭 to us in primary school, she didn't say 草船借箭 is a 成语 at all. It's just a famous story. And we rarely talk about this story.