I just found about a French mondegreen I carried in my head for 43 to 45 years or so

[pauamma]

In Colombine by Paul Verlaine, sung by both Georges Brassens and Maxime le Forestier, I misheard the last word of the fourth line, buisson (pronounced [bɥi.sɔ̃]), which rhymes with the next line, as ruisseau (pronounced [ʁɥi.so]) which would have (at least in my idiolect) rhymed with the second line. I'm not sure why I never noticed it would break the A A C B B C rhyming scheme (and, now that I think of it, the tune, as its last syllable is sung as the same note as the last syllable of the next line), but I suspect it's familiarity.