My vote has to go to William Shatner's rendition of Lucy in the Sky With Diamonds.

You can't possibly count that. You have to either vote on a bad SONG or vote on a bad PERFORMANCE. You can't say a song is bad just because someone covered it poorly. The original song is wonderful, and is a key part of one of the best and most-respected albums of all time. Yes, Bill butchered it, I agree.

Now, as long as we're talking about songs, I'd say my vote goes to Seasons in the Sun. I want to drill the evil spirits out of my cranium each time I think of it.