nest egg

nest-egg的词性：
n.（名词）

1. An artificial or natural egg placed in a nest to induce a bird to continue to lay eggs in that place.
留窝鸡蛋：放进巢中引诱鸟继续在此产蛋的人工蛋或真蛋

2. A sum of money put by as a reserve.
储备金：用作储备的一定金额