money for old rope
不劳而获，容易得到的东西或金钱
口语·形容不劳而获
英文释义
Easy money, effortless profit, or a valuable return for minimal effort
例句
Selling these old books online is money for old rope—they were just gathering dust.
典故来源
源于19世纪英国，旧绳子本无价值，但回收后仍可卖钱，比喻不费力的收益。