Mondegreens are the phenomenon of mishearing lines, normally song lyrics, but poetry is also a frequent victim. Sometimes it's lack of correct enunciation, sometimes it's the speed or pitch that a lyric is delivered at, but often, a song lyric or recited poem will become famous not for what it says, but for what it sounds like it says to the uncareful ear.
Sometimes caused by bad diction, or [...] [tvtropes.org]