The Booth Singer

A male or female who while karaoke is being sung in a bar sings along to every single song and knows every song. But they will never actually get up and sing one, and also they are not intoxicated whatsoever.

"my friend levi is such a booth singer he was just singin away to james blunt but when we asked him to sing a song he says no and just sings them all at the booth (therefore he is the booth singer)"