"A" is a song by South Korean girl group Rainbow. The song was released on August 12, 2010, and was later included on their second mini-album SO 女.
The "ab dance" featured in Rainbow's choreography was banned from broadcasting on September 8, 2010 due to it being "too sexual suggestive". The dance move involves the group lifting their shirts up but only up to the point where their abdomen or stomach can be seen before lifting it down again which was deemed similar to a 'strip tease'. The music video was also age-restricted on YouTube, but DSP Media retired the restriction. They started promoting the song without the "ab dance" in September 11. .