I am not even sure I knew this was a rumor but now I can't stop thinking about it.
Sam Smith was asked by Drew Barrymore what the craziest rumor they have ever heard before. They answered that it was that they were secretly Adele in drag.
They said, “Everyone thinks I’m Adele. We’ve never been seen in the same room together. If you slow down her voice, it sounds a bit like mine.”