When was the last time an airline made you smile? A just-released YouTube video of Delta employees flash-mobbing around the country may do the trick. Employees at airports in Atlanta, New York City, Detroit and at the Technical Operations Center, also in Atlanta, got in on the fun.

The video starts out a little boring, with a few Delta employees singing a cheesy-but-nice song about "Delta and you" and the places you'll go together. Then the video cuts to the crowd in Atlanta and … wham!  Delta flash mob!

One highlight is the flight attendant in the red dress in New York. She's on the right, and ever-so-slightly out of step with the rest of the group. Check it out at about 2:42. She eventually gets in the groove. Also, the guy at tech ops with his tongue sticking out the side of his mouth at 3:42  is pretty awesome, as well.

Delta spokesperson Ashley Black tells ABCNews.com there's even more to the video than meets the eye. Apparently, the flash mob video was conceived to surprise Delta leaders, from flight attendants to executives, at a conference last week. While the video was playing, about 100 of Delta's leaders who were in on the fun got up from their seats and performed the routine in the aisles.

Black said all employee participants did so voluntarily and on their own time.   She went on to say, "We hope the video shows customers what the culture at Delta is all about and that we  truly love to have fun."