指腹为婚指腹為婚

zhǐ fù wéi hūn

ㄓˇ ㄈㄨˋ ㄨㄟˊ ㄏㄨㄣ

Idiom

1to propose the future marriage of two unborn babies on condition that one turns out to be a boy, and the other, a girl (idiom)