A whole linguistic term exists because someone misheard a poem

In 1954, writer Sylvia Wright described mishearing a line from a Scottish ballad, 'laid him on the green', as 'Lady Mondegreen'. She coined 'mondegreen' for exactly this phenomenon: confidently mishearing a phrase, especially in song lyrics, as something else that also happens to make sense. The mishearing usually sticks because the brain fills gaps with the most familiar pattern it can find.

— Sylvia Wright, The Death of Lady Mondegreen — Harper's Magazine, 1954