But Friends' Phoebe Buffay might top them all.
Last Saturday night, actor Matt LeBlanc (who played Joey Tribbiani in the show) joined Swift on stage at her concert in LA’s Staples Center and it’s thought he may have helped her get in touch with his former co-star Lisa Kudrow.
Now the singer can officially count herself among the very select group who have had the pleasure of singing Smelly Cat as a duet with Phoebe Buffay.
With guitar in hand, Kudrow joined Swift on stage last night for a full rendition of the legendary a cappella song, which has since sent fans into a frenzy on social media.
The duet has also outdone the night’s other guest performances from Selena Gomez and Justin Timberlake.
The timely performance, which closed Taylor’s run at the sports stadium, comes in the same week as an Oprah interview from 1995 with the full Friends cast resurfaces.
The brilliant clip sees Oprah introduce the cast just as the sitcom had became one of the most watched shows on American TV.
But despite the raging success of the show, which we now know only got bigger and better, the quotes from the cast are surprisingly sweet.
Jennifer Aniston for example, confesses that she’s the least famous of the gang when Oprah asks them about being recognised on the street.
“I still just go to work every day. There are people on the street… but I don't get it as much as these guys and I don't feel it has changed my life this much."
Kudrow also adds: “If you're in LA, no-one cares, because there's bigger, better stars than us walking around.”
If only they knew that 10 years later Aniston would be gracing more magazine covers than most women in the history of celebrity, and Kudrow would be performing to a stadium of 20,000 people.
Images: Twitter / Words: Amy Lewis