SEOUL (Reuters) – A chubby, rapping singer with slicked-back hair and a tacky suit is the latest musical sensation to burst upon the world from South Korea, via a YouTube music video that has been seen by over 20 million people in under a month. In a nation famed for the pretty-boy but often bland bands of K-Pop, nobody was more surprised by the success of the video “Gangnam Style” than its creator, Psy, a musician with a decade-long career in his homeland who never thought to break overseas. “The YouTube video never targeted foreign countries. …