顺水人情 do sth. regarded as a favour without trouble to oneself; a friendly gesture without extra cost to oneself; a favour done at little cost 顺水人情不妨做做。 i don't mind doing you a favour that costs me nothing
顺水推舟 push the boat along with the current -- make use of an opportunity to gain one's end; make use of the favourable current situation to push matters through with little effort; push a boat in the direction of the current; turn any favourable factors to account so that the least effort would produce the results desired; go with the current; go with the crowd; do sth. without extra effort; take advantage of a favourable trend 既然他们坚持要去, 干脆我们就顺水推舟, 让他们一同去吧。 since they insist on going, we'll simply push the boat with the current and let them go with us
顺手牵羊 lead away the sheep by the way; (descriptive of) appropriating such things as come within one's reach, as one goes about one's way; go off with sth. near at hand; lead the goat away as a handy thing to do; make free with others' possessions; pick up sth. in passing [on the sly]; steal sth.; take quickly and secretly without permission; take sth. lying within easy reach; take sth. that doesn't belong to oneself; walk away [off] with sth.: 她顺手牵羊拿走了那顶新尼龙伞。 she picked up the new nylon umbrella on the sly