Leave it to a pop star to cause panic at an airport.

As Joe Jonas and Ashley Greene prepared to fly out of Abu Dhabi over the weekend, the 21-year-old Camp Rock 2 star mistakenly placed some knives in his carry-on luggage.

"We were going from the Middle East to New York, so [there was] tons of security, tons of screenings," Greene, 23, recalled on Lopez Tonight Tuesday. "We got through one, surprisingly enough."

By the time they reached the second checkpoint, the Twilight actress says airport security "looked at us with these stern faces like, 'What's in your bag?'"

Remembering that Jonas, an avid cook, had purchased a cheese-cutting knife set during their trip, Greene asked her beau of four months if he'd accidentally put them in the wrong bag.

Jonas' response: "Whoopsies!"

"Whoopsies doesn't cut it," Greene laughed. "We were going to get arrested!"

After explaining the mix-up, security allowed Jonas to stow his knife set under the plane. "It was embarrassing," Greene added.