How could I forget?
If we're discussing recent viral K-pop sensations, the only song that can really compete the Wondergirls' "Tell Me" is Jewelry's "One More Time." Wondergirls' youth and cuteness is put up against Jewelry's experience and sexiness. "One More Time" came out early in 2008, and the group placed number 1 for 7 weeks in a row on a popular music performance/rankings show. That's almost two straight months of dominating the Korean music charts and, more to the point, the internet downloads. Recently the group won a year-end award for 'Best Digital Single', which basically translates to 'Most Ridiculously Popular Song to Download, Performance to View on Repeat, and Dance to Imitate.'
The dance in question is the "E.T. dance," and if you watch the video, you'll understand why.
One More Time music video (with English subs, no less)
(I got pretty good at a tamer version of this dance, as well as the "Tell Me" dance. Both are remarkably useful phrases in an English classroom, and if doing a quick ET dance along with it is what it takes to wake the kids up at 8:30 AM, then so be it.)