This is a relatively new word (coined in the last century) that you probably aren't familiar with, but have experienced more than a few times.
noun 1. A misunderstood or misinterpreted word or phrase resulting from a mishearing of the lyrics of a song.
Etymology: 1950s: from a mishearing of the phrase laid him on the green, from the traditional ballad ‘The Bonny Earl of Murray’, as Lady Mondegreen
Source: Oxford Dictionary
So, there's a word for this phenomenon. I still sing Creedence Clearwater Revival like I did when I was six. Down on the corner, out in the street, Willy and the Coke boys are singing, Willy can 'git those happy feet. Oh John Fogerty, why must you sing with your mouth full of marbles? Here are some others that I think are pretty hilarious (via kissthisguy.com):
What are your mondegreens?
Erin Bedford, writer.