To fleece someone; to extort money or favors by taking advantage of their vulnerability or an opportune excuse; to overcharge unscrupulously.
那位店主经常利用顾客不熟悉行情，敲竹杠，价格总是比别人高出许多。
That shop owner often takes advantage of customers' unfamiliarity with market prices to overcharge them, always setting prices much higher than others.
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