"You can only have one for the rest of your life: weed, oral sex or cheese," the singer asks his BFF while taking over "Watch What Happens Live."
The inside jokes and banter flowed effortlessly between the longtime friends. Then John asked Andy to name a celebrity he's still salty about having turned down an appearance on "WWHL."
"Oh, wow, there are so many," Andy said. "I'm always wanting to turn them. You know what I mean?"
"Believe me, I know you like trying to turn people," John replied with a grin.
Andy said he wished he had his earpiece in so that his staff in the control room could help him out. John, who was wearing the earpiece, blurted out, "Michelle Obama!"
"Michelle Obama! Yes, absolutely, yeah," Andy replied. "I've given so much money. I've participated with them. I'm an enthusiast. I'm ready!"
John and Andy then bonded over having recently smoked pot with "Game of Thrones" novelist George R. R. Martin, which prompted Andy to brag about the other famous stoners who made his "amazing" pot list: Willie Nelson, Snoop Dogg and Bob Weir from Grateful Dead.
John then posed the evening's second-most daunting question: "You can only have one for the rest of your life: weed, oral sex or cheese."
"I love cheese, but I'm taking that off the list," Andy said before reaching the conclusion that he couldn't live without oral sex. Of his beloved marijuana, Andy said he'd "have to find another vice."
"I'm going to pick Anderson, and here's why," Andy said. "He is a catastrophist. There was a moment a year ago or 8 months ago where I thought we were gonna be in a nuclear holocaust, and I was talking to him about it, and he understood what the world would be in that situation in a way that I had never thought about. And he had so many survival techniques, so I actually think that he could keep us alive the longest."
Andy then gave a heartfelt thank you to his staff, his viewers and his dear friends for what he called "9 years of glory" on Bravo's late-night platform.
In another delightful moment, John thanked Andy for introducing him to famous people who would otherwise want nothing to do with him because of his star-studded list of exes.
"You have a lot of friends who, without you, would want nothing to do with me -- and I find that exciting," John said. "You know what I mean? You're friends with Jennifer Lawrence, who just doesn't want anything to do with me. Look, I don't have the world's greatest track record when it comes to celebrity relationships, so it's amazing to watch your friends humor me on a friend level, but also keep a fair distance from me."
"It's really, really fun, because if you are someone who cares about your image -- and you take this job because it looks right, you don't take that job -- dating John Mayer at this point is conceptually just sort of a no-no," the singer added. "So, it's really fun to get to hang out with your friends -- A-list star friends -- who otherwise would be highly uncomfortable sitting around me. And I want to thank you for that."