Watch Jessie J sing 'Bang Bang' with her mouth closed

Pop star Jessie J recently stopped by the Graham Norton Show to discuss the Grammys, the repetition of popularity and show off a party trick.
"I just did the Jingleball tour all over America, and the reaction to 'Bang Bang' was just so overwhelming," Jessie J told the guest panel when asked if she gets bored with performing "Bang Bang," her Grammy-nominated collaboration with Ariana Grande and Nicki Minaj.
"But [I] sometimes feel the audience when I sing [4-year-old single] 'Pricetag' like 'Uhg, there's that money money song again.'"
The conversation eventually turned to Norton's appreciation for the diva as a "chat show" guest because of her always-entertaining ability to sing with her mouth closed. Far from a Milli Vanilli-style lip-syncing controversy, what Norton meant was Jessie J's ability to literally sing for a notable period of time while containing her lungs' expelled air inside her mouth.
Jessie J says she picked up the trick as a child by impersonating the voice of someone stuck in a box.