Actually, sexy dance should be one word. It's more of a compound noun, because the dances certainly can't be described as "sexy." On an earlier post I promised that if elected president of South Korea I'd ban ddeok from public consumption---the noisiest food in Korea---and would outlaw sexy dances.
"Sexy" was #1 on my list of "Ten most hated English phrases in Korea" in 2008, and it has a hell of a chance to repeat this year. I've also covered sexydances a lot on this site before because they are absolutely ridiculous. Granted, about half of the sexydances I've seen have been from middle school students at English camps and talent shows, but . . . well, perhaps that tells you a lot right there. I think some of the best commentary on this comes from "Qinella" on a Dave's thread a few years ago:
Is it possible to watch Korean women dance around and not just laugh? I remember this girl I met during my first year in Korea gave me a naked "sexy dance". I was laughing and told her to never, ever try to be sexy again. And it seems like they all do the same goofy dance.
A few examples I've collected on this site:
That's the exceedingly dull Son Dambi, now ubiquitous ad-girl and frontwoman of Korea's Pussycat Dolls. No, they don't know what pussy means. Here's a young woman dancing at a ceramics festival.
Sexydances share a few set moves. The women like to stomp, jerk their shoulders around, do a half-squat every now and then, look off to the side, and run their hands through their hair (see, for example, the woman on the right in the first picture). Bonus points for laughing or scrunching up your lips. Finally, inevitably, the dancers will attempt to back it up. Around 1:00 into the Son Dambi video you'll see the dancer try it, and at 1:36 of the second video she gives it a go. Once they do that move I can no longer keep a straight face. Like many other things in Korea, the dance moves are adopted without any context, and these dancers likely haven't learned that they need something to back up.
I'm not sure how far back the trend of unsexy sexydances goes, but this 2005 video from Jewelry seems quite influential.
Skip to about 2:00 to see all the hallmarks of a Korean sexydance.