log·roll·ing
noun/ˈlɒɡrəʊlɪŋ/
/ˈlɔːɡrəʊlɪŋ/
[uncountable] (North American English)- (especially in US politics) the practice of exchanging favours, especially by agreeing with somebody that you will vote to pass a law that they support so that they will later vote to pass a law that you support
互投赞成票（促使议案通过） - a sport in which two people stand on a log floating on water and try to knock each other off by moving the log with their feet
水上滚木比赛（两人同时站在浮于水面的圆木上设法转动滚木使对方落水）