Appearing on The Graham Norton Show last Friday (16 January) Jessie wowed viewers as she sang her recent number one hit with her mouth completely closed.
After Graham revealed she has a pretty unique talent, the 26-year-old then put on a special performance for the viewers watching.
Not holding back, Jessie went straight into the opening line of 'Bang Bang' and apart from obviously being a little muffled, the singer was pitch perfect as she hit every note.
How she does it, we just don't know! Mind. Baffled.
Like us, the other guests - including Broadchurch stars Olivia Coleman and David Tennant - were taken by surprise at Jessie's closed-mouth rendition and burst into applause as the raven-haired beauty finished.
As well as revealing her much-loved party trick, Jessie also let slip the reason why she loves high-waisted clothing so much.
Chatting to Graham, the starlet admitted she has an unfortunate misspelled tattoo inked on her side.
She explained: "I had 'Don't lose who you are in the blur of the star!' tattooed on my side. Not long after I had it done my mum said to me in tears, 'I don't know how to tell you this but it is spelt wrong.
"I have 'Don't loose who you are in the blur of the stars!'. It's the reason I always wear high-waisted stuff. I'm not going to put a spelling mistake that close to a camera!"
Meanwhile, Jessie - who is currently dating US singer Luke James - will be stepping back into her coaching shoes as she joins The Voice Australia for its next series.
Replacing Kylie Minogue, Jessie will sit alongside Delta Goodrem, Ricky Martin and The Madden brothers (Joel and Benji) as they search for the next singing sensation Down Under.
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Watch Jessie J sing 'Bang Bang' with her mouth closed in the video below: