kick with the other foot
1. To belong to a different religion or religious order, especially either Protestantism or Catholicism. Primarily heard in Ireland. My devout Catholic parents wouldn't allow me to marry Sean because they said he kicked with the other foot.
2. To be homosexual. (Usually used in reference to athletes as a pun on the act of kicking a ball.) Primarily heard in UK, Ireland. Though there are undoubtedly many professional footballers who "kick with the other foot," there still exists a persistent homophobia in the sport that precludes them from coming out openly.