Watch Jessie J Sing 'Bang Bang' With Her Mouth Closed

— -- As a child, Jessie J. learned that she had a pretty great hidden talent: She could speak clearly with her mouth closed.

However, it came in handy professionally too.

"When I was younger, I actually did an audition -- I used to do auditions all the time -- and I was asked what I could do," she explained during an appearance on "The Graham Norton Show." "I discovered I could pretend that I was in a box."

Later, the self-described "lonely child" realized that her party trick was even cooler than she first thought. Why? She could sing with her mouth closed too.

In the video below, the Grammy nominee demonstrated the trick by singing a few lines from her hit song, "Bang Bang," causing the audience to erupt in applause.

"Ta da!" she said.