ANSWER
Mondegreen.
The word "mondegreen" was invented in 1954 by writer Sylvia Wright. It refers to a Scottish Ballad called "The Bonny Earl of Murray", one verse of which goes as follows...
Ye Highlands and Ye Lowlands
Oh where hae you been?
They hae slay the Earl of Murray,
And Lady Mondegreen.
Sylvia always wondered about Lady Mondegreen, so loyal to the Earl that she was willing to die with him. It wasn't until several years later that she discovered the REAL words to the ballad...
Ye Highlands and Ye Lowlands
Oh where hae you been?
They hae slay the Earl of Murray,
And laid him on the green.
Columnist Jon Carroll maintains one of the better websites devoted to mondegreens at http://www.sfgate.com/columnists/carroll/mondegreens.shtml
WHO GOT IT RIGHT: Kristy Morgan, Cindi Lou, Pete Daggett, Marc Quinlivan, Bob Milligan, Robin Campbell, Marika Thiessen, Cindy Olmstead, Jim Ahumada, David Evans, Yanitz Grinell, and Moana Kutsche.
