bat for both sides
1. To play for or support two opposing sides in a given contest or debate. Refers to cricket and baseball terminology, meaning to be a batter for both teams during a game. Many feel that the congressional candidate is trying to bat for both sides in the debate on tax reform. We didn't have enough kids to make two full teams, so I ended up having to bat for both sides.
2. To be attracted to or have sexual relations with both males and females; a euphemism for being bisexual. Jim is currently dating Steve, but I know that he bats for both sides.