Katy Perry and Rihanna
Though the pair reportedly had a falling out over Rihanna's relationship with Chris Brown, Perry couldn't help but take a playful jab at her pal during a 2013 chat with Elle Canada. "I think that Rihanna always looks so fresh and I'm like, 'How do you do that? We all know how much pot you smoke! And you don't sleep because you're on Instagram at four o'clock in the morning!'" she said with a laugh and a wink, calling out Rihanna's unapologetic marijuana use and selfie-prone tendencies.