Katy Perry Ranks Her Ex-Boyfriends in Bed, Reveals the Surprising 'One That Got Away'

You'll never guess who it is!

Katy Perry kisses and tells!

The "Swish Swish" singer shockingly revealed her personal romantic ranking to James Corden during her 72-hour YouTube livestream on Sunday, in the lead-up to the release of her new album, Witness.

WATCH:Katy Perry Previews New Album 'Witness,' Goes Live on YouTube in 'Big Brother'-Style House

The ratings came during a question and answer game with Corden, where the alternative to answering was to consume a questionable snack.

The Late Late Show host asked the 32-year-old pop star to rank her exes from best to worst in bed, "working on the notion that they're all good."

Perry protested vehemently at first: "They're all amazing lovers and I would have sex with all of them after I get out of this place!" she told Corden. 

Eventually. her final ranking listed Diplo, whom she dated briefly in 2014, at the bottom, followed by recent ex-boyfriend Orlando Bloom, with John Mayer -- with whom she had an on-and-off relationship that ended in 2015 -- at the top.

But there was one more man worth mentioning: Josh Groban, whom Perry referred to as "the one that got away," after they were linked together in 2009. 

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Perry inhabited a Big Brother-style house for the duration of the livestream, opening her life up to the public for 72-hours,which included an emotional therapy session.

Find out more in the video below.