British couple banned from U.S. after tweets

For two young British tourists, it was the trip of a lifetime - but for all the wrong reasons. Following a telephone tip-off to U.S. officials, Border Patrol agents were waiting when Leigh Bryan and Emily Banting stepped off the plane at Los Angeles International Airport.

"I kept saying this is a mix-up," Bryan said. "Someone is going to come in a minute and say, 'Oh no. Sorry. This is stupid.'"

They say Border Patrol Officers began grilling them about a Tweet Leigh sent to friends before their trip, "Free this week for a quick gossip/ prep before I go and destroy America?"

They tried to explain "destroy" is British slang for partying hard.

Watch: Should Homeland Security monitor social media?

"If you're hungry and you go to McDonald's - you say I'm going to go 'destroy' a McDonald's," Bryan said. "Or if you're going out to a nightclub, say the nightclub was called Caesar's Palace, to get drunk, you say you're going to go 'destroy Caesar's Palace.'"

After being held in a detention center, the couple were sent packing on the next flight home.

Officially, the Department of Homeland Security says they were denied entry because their visa waiver paperwork wasn't in order.

To see Charlie D'Agata's report, click on the video in the player above.