Jack Black flaunts his flexibility and his underwear while singing a Taylor Swift song at fundraiser

Jack Black is celebrating the 1989 (Taylor's Version) release just like the rest of us.

At the Give Back-ular Spectacular fundraiser event in Los Angeles on Wednesday, the School of Rock actor donned nothing but socks and his tighty-whiteys (er, tighty-rainbows?) as he took song requests. He eventually settled on Taylor Swift's "Anti-Hero," insisting, "yes, I know that one… everyone knows that f---in' song."

The Tenacious D singer proceeded to belt the chorus of Swift's song without accompaniment, showing off his flexibility with high kicks as he sang to the crowd. And despite his insistence that he knew the song, he quickly descended into his signature gibberish-singing after appearing to forget the lyrics.

Black also rejected a request for a different song because "we're in a strike," presumably because the song in question was tied to one of the actor's films, and SAG-AFTRA members are not permitted to promote their past or future work until the end of the strike. He also said "you don't have to film it on your phone" to a member of the audience, but the clip still made its way to social media anyway.

The Give Back-ular Spectacular was organized to raise funds for crew members impacted by the ongoing SAG-AFTRA strike and the recently-wrapped WGA strike, which shut down production for most of Hollywood's movies and television series. Organized by the Union Solidarity Coalition, the event raised over $500,000, according to the organization's social media page.

The event also featured appearances by Bryan Cranston, LeVar Burton, Lily Tomlin, Patton Oswalt, and numerous other entertainers.

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