Dwayne Johnson‘s been spilling the beans about his bathroom habits — turns out he sometimes pees in bottles while filming. The former wrestler-turned-movie star opened up about this quirky practice in a recent GQ video cover story. He explained it’s all about being efficient, as taking bathroom breaks on set can eat up precious time. “Yeah. That happens. … I’ve said a thousand times: ‘Hey, I’m here. Come and ask me. And I’ll tell you the truth,’” Johnson shared with the magazine, brushing off concerns about what happens to these bottles afterward. This revelation about Johnson’s on-set routine…