Quick! Name three of the groups currently holding top ten spots on Billboard’s newish K-Pop chart. If you passed that test, skip to the video below (or go back to your rigorous YouTube-watching schedule); if not, let’s spend a moment to get acquainted with Girls Generation, the Korean girl group that made its national television debut on Letterman last night. They are, as you might have guessed, huge in Korea; they are also big in Japan, which is no small feat given that country’s singular devotion to its own J-pop; and they will be trying their damndest to be important in this country, too. That effort kicked off last night on Letterman, and while this live performance of “The Boys” doesn’t really live up to its video (what can?), it is certainly worth watching just to catch the look on Regis Philbin’s face around the 2:45 mark. He looks stunned, but sort of pleased? That is exactly how it feels to watch your first K-Pop video!