Meaning:

敲竹杠 (qiāo zhúgàng) fleece; take advantage of sb.’s being in a weak position to overcharge him

Usage:

“敲竹杠”指利用别人的缺点或弱点来索取财物或讹诈。经常用作“敲某人的竹杠”。

“敲竹杠”refers to ask for or blackmail someone who is being in a weak position. It’s often used to be “敲某人的竹杠”.

Examples:

1. 这个饭店特别喜欢敲客人的竹杠，现在都没有什么生意了。

    Zhè jiā fàndiàn tèbié xǐhuan qiāo kèrén de zhúgàng, xiànzài dōu méiyǒu shénme shēngyi le.

    The restaurant has little customers because it always overcharged.

2. 你可不能敲他的竹杠，他已经够穷的了。

    Nǐ kě bù nénɡ qiāo tā de zhú ɡànɡ, tā yǐ jīnɡ ɡòu qiónɡ de le.

    You’d better not extort him as he is so poor.