The pair have sparked speculation that they are dating due to their close friendship, and even addressed the rumors.
Andy Cohen and John Mayer appeared together in celebration of Cohen's 50th birthday, and during the course of their conversation they wondered out loud if people thought they might be secretly dating.
The segment of Watch What Happens Live With Andy Cohen featured Mayer asking the talk-show host audience questions, and even singing him a special rendition of Diana Ross' It's My House.
Cohen was touched by the gesture, because Ross is his favorite artist.
Mayer shared that he had spent the previous 48 hours doing nothing but learn the song especially for his friend.
"I have done nothing but learn that song in the last 48 hours," he said. "I have ate, breathed and slept 'It's My House,' and I am now a fan of that song!"
The pair discussed their close friendship, and Mayer admitted that he loves hanging out with Cohen's friends, because his dating history tends to make celebrities nervous around him.
"If you are someone who cares about your image...dating John Mayer at this point is conceptually just sort of a no-no," Mayer said. "So it's really fun to get to hang out with your friends, your A-list star friends, who otherwise would be highly uncomfortable sitting around me."
And on that topic, the pair seemed to get very intimate for a moment when Cohen slyly confessed to "knowing Mayer's body" after the singer video chatted him while naked in a sauna.
There were some snickers from the crowd, and the pair got to talking about whether people think they are in a secret relationship.
Mayer immediately noticed that Cohen's staff in the background were all nodding, but the men didn't exactly deny anything as they went in for an awkward high-five/handshake.
"See, I tried to give you a straight high-five and you gave me a gay [handshake]," Cohen said, to which Mayer replied: "My nails are still wet."