Loudon Wainwright III - "Dead Skunk," "The Acid Song," and "Motel Blues." I've written before about how much I wish I liked Wainwright more than I do. On paper it looks like I'd be a big fan of his. In reality, though, he sorta grates on me.
Not Louis Armstrong - "Oops I Did It Again." Here's the parody hit that went around the web some years back. See, the joke is that Louis Armstrong is a giant of jazz and here someone who sounds a little like him is performing a version of Britney Spears' "Oops I Did It Again." Hilarity! I mean, sure, Armstrong performed a lot of popular songs from different periods, and presumably would have been happy to record a song like this. But he didn't! And Britney Spears is a girl making girl music, which just adds to the hilarity. Next thing you know, these guys will have a version of someone equally unlikely performing this song. Maybe even Richard Thompson!
Louis Jordan - "Beans And Cornbread." Some might think this is the greatest song of all time. They might be right. I had a full album of Louis Jordan songs, too, but it somehow got corrupted. Boo.