Please welcome to the stage...someone we'd have sooner expected to spot in line at the nearby grocery store's checkout.

Last night (August 24), at the latest stop along Taylor Swift's 1989 tour (and one of five shows at Los Angeles' Staples Center), the country-gone-pop singer invited the breakup song's primary architect, Alanis Morissette, to perform her biggest hit. And though Swift was only five when "You Oughta Know"—which celebrated its 20th birthday in June—was released, she nevertheless sang its praises.

"She inspired a generation of confessional female singer-songwriters, who all of a sudden felt like you could actually say these raw feelings that you have," Swift says to her audience in the clip above. "So many of the female singer-songwriters of my generation, including myself, would not write the way that we do without her and her music."

Now 41, Morissette manages to tap into her signature early-20s angst in the clip, and—dressed in dueling leather ensembles—she and Swift make a pretty convincing tell-off team. (Spoiler alert: The tune's most obscene lyrics are still very much do you like that, L.A.?)

Alanis is the latest in a long line of celebrity guests invited by Swift to join her on stage—Mary J. Blige, Ellen Degeneres, Joan Baez, Little Mix and Julia Roberts are just a few of the most recent.

Is this jagged little pill just what the doctor ordered, or should it have been left behind at the pharmacy? Share your thoughts in the comments!

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