It's not actually a line in the song, but rather a misheard lyric. The actual lyrics are:
*"We think you're a joke"*.
However, because of the way the song is sung and the distorted audio on the show, it can be easy to mishear it as *"We think your a joke shove you where it shine"* which is a great example of a "mondegreen" – a misheard word or phrase.