I fought the lawn and the lawn won.

The story:

So its actually my mum who made this mistake. We
were at my music school's concert, and the acoustic
guitar group was playing this song as a sing-
along. So we're all very into it, and singing at
the tops of our voices, and I hear my mum singing
'lawn' instead of law in the prisoner's song. I
told her afterwards, we laughed tremendously and
she said she had thought the song was about someone
struggling with a lawnmower (she just spends too
much time gardening!)