I stumbled on the Korean version when I watched the Making of clip for You're Beautiful. This is another case of 'stumbled on'... a short clip of this was inserted at the very end of Cartoon KAT-TUN ep 36.
Well, if a song is good.. it's good in any language, I guess. I tried to find the original version by Boney M. (supposedly) but couldn't. Maybe it's too old... and I dunno what the title is for that version.
By the time everyone takes off their clothes, I just had to stop dancing and I spent the rest of the time gaping at the TV monitor. Errr.. coz I heard 'hadaka de' being mentioned and thought that I have to concentrate on the visuals instead of prancing around my living room at 2.30 in the morning.. *cough*