When all 236 episodes of Friends hit Netflix earlier this year, it quickly became one of the streaming service's most watched TV shows. 90s nostalgia is at an all-time high, and the popular NBC sitcom, which ran from 1994 until 2004, is at the epicenter of this tsunami. While there is no word on a Friends reunion series happening anytime soon, one of the more popular elements to emerge from the comedy got revived last night, and it sent a crowd of thousands into a screaming fit.

The reigning queen of pop and country, Taylor Swift had a big surprise awaiting fans at last night's concert, where she was performing live at L.A.'s Staples center. And she saved her best special guest for the encore. Closing out the Los Angeles-leg of her '1989' world tour on Wednesday, she shocked the crowd when she brought one of the iconic Friends on stage.

RELATED: Courteney Cox Waited Two Decades to Get Her First Emmy Nomination for Friends

Sure, it was Lisa Kudrow. But the comedic actress was introduced as Phoebe. This was a 'rare appearance' by an up-and-coming singer who's only previously 'played in coffee houses'. Once on stage, Lisa Kudrow and Taylor Swift broke into a duet of Phoebe's signature tune 'Smelly Cat'. We have the full video here for you.

Smelly Cat made its television debut in the Friends Season 2 episode The One With the Baby on the Bus. The song is first mentioned in passing in a conversation between Pheobe and Rachel, but at the end of the episode, Phoebe teaches it to guest star Chrissie Hynde, where it is sung for the first time. In a later episode, the song returns when Phoebe makes a professional recording of it for release in record stores nationwide. But her voice is replaced by a much older singer. Here, we also get to see a music video for Smelly Cat, which later appeared on a DVD release of the show.

During the course of Friends, Smelly cat would make quite a few appearances. The song is even used as a jingle in a litter box commercial. Friends Season 5 even goes as far as to delve into the deep-rooted origins of Smelly Cat when it is revealed that Phoebe's father used to sing her to sleep with a song he called 'Sleepy Girl', which sounds a little too much like Smelly Cat. The song would also later appear on the Friends Again soundtrack, and was credited to Phoebe Buffay & The Hairballs (featuring the Pretenders). Chrissie Hynde also released a hard rocking version of the ditty. But perhaps no rendition is as epic as the one we hear in this duet between Taylor Swift and Lisa Kudrow.