kara-croaker

1.) A person who insists on singing karaoke, even though they are unaware that they are tone-deaf, off-key or just otherwise bad.

2.) A karaoke singer who chooses a very good song, and then proceeds to murder it beyond recognition.

3.) A karaoke singer who picks a song that gains many a groan from the audience.

"Why does Shayla always insist on droning her way through 'The Rose'? What a kara-croaker."

"The rotation has more kara-croakers than singers tonight."