Mondegreens are a sort of aural malapropism. Instead of saying the wrong word, you hear the wrong word.
The word mondegreen is generally used for misheard song lyrics, although technically it can apply to any speech.
"Excuse me while I kiss this guy."
"Excuse me while I kiss the sky."
Purple Haze, Jimi Hendrix
"The girl with colitis goes by."
"The girl with kaleidoscope eyes."
Lucy in the Sky With Diamonds, The Beatles
"Are you going to starve an old friend?"
"Are you going to Scarborough Fair?"
Scarborough Fair, Simon and Garfunkel
See full list at http://www.fun-with-words.com/mala_mondegreens.html