money tree
noun
1- US a source of easily obtained or unlimited money〈美〉摇钱树：
I knew how to shake the money tree.
我知道如何摇摇钱树。
1.1
- a real or artificial tree to which people attach paper money, especially as a gift or donation礼钱树（真的或人造的树, 可附钱于其上, 尤指作礼物或捐赠）。