Apparently, this strange song is all the rage in Japan: Oshiri Kajiri Mushi (or the Butt Biting Bug). From Global Voices Online:
A catchy tune about a funny-looking bug that bites people’s bums and makes them happy is catching on like crazy across Japan. “Oshiri Kajiri Mushi“, a short clip featured as regular filler between programs on the national broadcaster NHK as part of the children’s show “Everybody’s Song” [Ja], has crossed the age barrier and is rapidly becoming a hit among adults as well. With all its popularity, CDs of the song, released on July 27, sold out earlier this month, and NHK has meanwhile decided to extend regular airing of the clip on TV through August and September.