Not quite a mondegreen, but hilarious anyway! Cliff Richard's song was always sung thus among my associates of the time "All my life i've bin kissin; your left tit, 'cause yer right ones missin' OH BOY!
BUT the classic is by the ever great Bridie Gallaher who could make the telephone directory sound delightful if she sang it, on one of her early recordings, either "Moolight in Mayo" or "Girl from Donegal" sings "The Emigrants Letter" beautifully as always, but misconstrues a word. It is of course an emigration ballad, the lad has left his girl and family behind but is writing to console them and to reassure them that he is being treated well, and so he writes in high-falutin' english that he has "Lots of COMBUSTABLES piled on his plate" I rather think it Should be COMMESTIBLES, that is eatables, and not fire lighting material!!!
Now the strange thing is that every other recording of that song makes or remakes the same error, and I know a few!