During a Truth or Dare-type game, the British host asked Katy to rank three ex-boyfriends from worst to best according to their performance in the bedroom:
Diplo, who she dated for a few months in 2014.
John Mayer who she had an on-off three year relationship with until late 2015.
And Orlando Bloom, her most recent boyfriend who she dated for 10 months.
Despite initially throwing a mock strop at the thought of revealing something so personal, the 32-year-old quickly opened up, listing Diplo as worst, then Orlando, then John.
However she was quick to insist: ‘They're all amazing lovers and I would have sex with all of them when I get out of this place!’
The singer – who is taking part in the live stream to promote her new album Witness - also revealed that Josh Groban is ‘the one who got away.’
‘People are like, who's the one who got away? That's Groban,’ she spilled. ‘He's one of my good friends. I love him so much. He's the best.’