Ideas for book writing

I'm looking to see if anyone has Ideas for any book writing.

A few I've thought about recently were the following:

1. Children's book on a hundred and one ways to walk to school backwards.
2. Children's book on the best way to fry worms so Mum won't know.
3. Children's book on what to do with the wax in your ears.

you see, I'm having a bit of difficulty coming up with some unique ideas. Any constructive (somewhat tasteful - for age 10-15) would be helpful.

Cheers,

Mark