Actress and singer Anna Kendrick is shocked by the success of her song 'Cups' featured in the movie 'Pitch Perfect'.  Kendrick say's that she is shocked by the success of the song which has been on the charts for a few weeks now even though it was released eight months ago.  Kendrick is offering an appology to parents everywhere too, it seems that some kids have become obsessed with the song and using a cup to sing along with it.  So much so that kids have made how to videos on how to play the cup and sing the song.  Anna Kendrick actually Tweeted, "Dear parents that I meet, I know that sigh, and before you even say it, I'm very very sorry that your child won't stop doing Cups."  I'm sure there was a song that you were obsessed with when you were a kid and drove your parents nuts!