shùn​shuǐ​rén​qíng

favor at little cost

Senses

顺水人情/ 順水人情 shùn​shuǐ​rén​qíng favor at little cost

to do someone a favor without any extra effort, or to help someone by taking advantage of a situation that already exists; literally "a favor following the current of the water"

References

synonym 惠而不费/惠而不費 顺水人情/順水人情