Update, 11/12: Madonna continues to grace her 'Rebel Heart' world tour with some A-List guest appearances a la Taylor Swift. Rita Ora was the latest star to get up on-stage alongside the Queen of Pop at last night's Berlin concert. Keeping to her tour guest tradition, Madonna gave Ora a spanking while performing "Unapologetic Bitch" before sharing a banana with the Brit singer (because, how else would you welcome your tour guests?). Watch the duo's mini performance from last night's show below: 

 
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Other 'Rebel Heart' tour guests have included Jessica Chastain, Idris Elba and Katy Perry. 

 

Original Post, 10/28: Giving Taylor Swift's star-studded '1989' tour some serious competition, Madonna had a special surprise guest of her own during last night's 'Rebel Heart' concert—Katy Perry. The Queen of Pop brought the California Girl on-stage for an unrehearsed, slightly bizarre performance of "Unapologetic Bitch" which ended with Madonna spanking Perry for being a "bad, bad, bad girl"—because, of course. 

Before exiting the stage, Katy Perry bowed down to Madonna and yelled out, "I love you mom!" The duo also then shared a banana on stage together because, you know, daily fruit intake is very important—even for popstars.