One specialized form of poem/song is the parody. It keeps the same structure and tune, if appropriate, but the words are revised as necessary. Anyone who has seen The Capitol
Steps perform is very familiar with song parodies. Parodies often use many of the same words as the original poem, even though the meanings and purpose of the poem is twisted. One fine parody is Ian Robb's
"Garnet's Homemade Beer" based on Stan Rogers' "Barrett's Privateers." The latter has a line: "Here I lay in my twenty-third year." The former changes that to: "Here I lay in my twenty-third beer."
Parodies are a lot of fun, but could engender lawsuits or hurt feelings. You might want to be careful of this, especially if you are parodying the work of friends. Jez Lowe had an incident where some people
he was touring with would constantly parody his songs. He was very upset about it because he had labored long and hard over his songs to try to make them something good or beautiful, and here were these gents who
were cheapening the songs by making them into inane ghosts of themselves. In Mr. Lowe's case, he only writes a handful of songs every year. He might devote two months of constant rewriting to get one song to a
point where he is satisfied. He finally drove home the point of how it made him feel by parodying a serious old folksong that was part of one of the other gentlemen's repertoire. The other fellow was scandalized
that he should do such a thing.
So, be careful, but enjoy the possibilities.