Mandy No Moore
Over the years, many people have sent around many YouTube videos of terrible singers performing terrible versions of popular songs from their homes. But in my humble opinion, this girl's rendition of Mandy Moore's "Crush" is up there with the worst. She starts off badly and goes down from there, even throwing in a coughing fit at the end. The only thing that could've made this video more humiliating would have been if the girl had tried to use a monkey, like Mandy did in the original video.*

Onto another performer who's been having trouble singing lately, here's some footage in which Amy Winehouse may be snorting cocaine onstage, mid-sing, in front of an entire audience.

* Why do I know that fact? I wish I had a good answer to that question. I could try and blame it on writing for TRL, but I definitely wasn't working there when that video came out.