When HBO Max launched last year, one of its marquee attractions was supposed to be a reunion of the cast of Friends, and each of the cast members reportedly got paid millions to do it. Now, after a solid year of pandemic-related delays, that Friends reunion is finally up on HBO Max. It’s got James Corden interviewing the show’s cast on a recreated version of the Friends set, and it’s also got a few famous guests. One of those guests is Lady Gaga, who sings “Smelly Cat” with Lisa Kudrow.

Kudrow’s character Phoebe Buffay first sang “Smelly Cat” on a 1995 episode of Friends, and the song made a few appearances on the show over the years before becoming one of the most weirdly enduring artifacts of this weirdly enduring show. (Kudrow and Taylor Swift sang it together at one of Swift’s shows in 2015.) On the reunion special, Kudrow sang “Smelly Cat” before Gaga came through with her own acoustic guitar to sing it in full theatrical-howl mode. There’s also a fun twist to the performance that I’d rather not spoil. You can watch it below.

There were other pop-star guests on the show, too. BTS, for instance, joined the parade of celebrities who added little bits about how much they loved Friends, while Justin Bieber wordlessly modeled Ross’ Spudnik costume during a fashion-show segment.

Vice reports that the Friends reunion is also airing in China, on various streaming services, but that the appearances of Gaga, Bieber, and BTS were all cut from the Chinese version of the reunion. Gaga has been banned from Chinese TV after meeting with the Dalai Lama, Bieber has been banned from performing in the country for “bad behavior,” and BTS have faced criticism after group member RM said nice things about American involvement in the Korean war.