If you've seen more than one episode of Friends or have been alive in the United States of America for more than a few years, you're familiar with "Smelly Cat." Phoebe Buffay serenaded the coffee-fueled denizens of Central Perk with the pitchy acoustic number in the second season of Friends, nabbing an instant Hot 100 hit in the minds of TV watchers everywhere.
Taylor Swift was five years old when "Smelly Cat" debuted; two decades later, she brought actress Lisa Kudrow onstage—introducing her as Phoebe—to duet on the song at a sold-out Staples Center in Los Angeles. Kudrow went on to tweet that Taylor is "THE best person I've ever met." Tay's take? "Never thought I'd say this but 'Smelly Cat' was on my set list last night. @LisaKudrow, you are the greatest."
Since this is the 1989 Tour—the one that featured Alanis Morissette and the Dixie Chicks' Natalie Maines and Ellen DeGeneres all in one night—"Smelly Cat" wasn't the only famous-person-aided cover. Justin Timberlake also showed up for "Mirrors"...
...and Ms. Selena Gomez came out for a duet of her recent single, "Good for You":