Sir Paul McCartney and Beck performed together Wednesday night for animal-rights organization People for the Ethical Treatment of Animals' 35th anniversary gala in Hollywood, singing a couple of Beatles songs including "I've Just Seen a Face" and "Drive My Car," according to Spin.

Before Beck joined him on stage, the former Beatles man first sang some Beatles fan favorites including "Let It Be", "Hey Jude", and "Lady Madonna." McCartney also sang an animal-rights-themed number he wrote called "Looking for Changes," which is about the various forms of cruelty and torture animals go through in laboratories, such as cosmetic tests on rabbits and tobacco experiments on primates, according to Consequence of Sound.

"When I first heard the name, that's what appealed to me, People for the Ethical Treatment of Animals," McCartney said during his performance. "I thought that was really a very dignified, very cool title. They've got 35 years of saving so many animals. And we love them."

The evening included a humanitarian awards presentation, hosted by Pamela Anderson and Anjelica Houston. Tommy Lee received an award for his help towards PETA's campaign against SeaWorld, and RZA won an award for his vegan campaign. Other A-Listers who attended the event included Kesha, Rob Zombie, Moby, Black Sabbath bassist Geezer Butler, No Doubt bassist Tony Kanal and AFI frontman Davey Havok, Rolling Stone reported.

"Thanks to @beck and everyone at #PETA35!" McCartney tweeted Thursday morning. "Sorry we didn't get to play Beck In the USSR, Get Beck or Paperbeck Writer!"

Sir Paul and Sir Beck!!! #PETAGALA A photo posted by Kevin Nealon (@kevinnealon) on Sep 30, 2015 at 11:07pm PDT

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