here are a few ideas

1) ransom letter. make the writing style absurd or archaic. make the demands preposterous. tell us why you are doing what ever you are threatning to do...

2) ask the most ridiculous questions that you could come up with.

3) explain the 'true' meaning of a famous song.

4) pit.yourself aganist yourself; write a piece, where you prove and support something you truly don't agree with.

5) write a recipe , where some ingredisnts are from different forms of art ( literature, music, plastic arts) .

6) complain bitterly on something that most people would love to have

7) two rats fell into a vat of cream. one drowned , the other survived by floating on the butter the first rat churned. write a dialogue of how it went down.

8) describe in great enthusiasm a very mundane moment (let's say, waiting for the copt machine to warm up).

9) write about your normal day as an odessey.