There is a term for this phenomenon, and it is a 'Ladymondegreen', after someone thought that was the line when it actually said 'laid him on the green'.

For years as a kid I sang 'Bumbading Badonna' to the opening line of UB40's Ivory Madonna

I also made up a word to fit the Stranglers classic 'Golden Brown' with the line 'with my mansheerun'. A relative of Ed Sheeran perhaps? I looked up the real lyric a few years ago.

A more recent one I had debunked by my GF was my decades long belief that Feargal Sharkey sang 'A good heart it says is hard to find'.

Although revenge was mine the other day when I explained that Wham sang 'Fun and sunshine, there's enough for everyone, all that's missing is the sea' but she had always just mumbled nonsense to fill that last bit.