William - the Pirate by Richmal Crompton
First off, this book has absolutely nothing to do with pirates and I'm not sure how the title was chosen.
I used to enjoy reading Richmal Crompton's stories of the mischievous boy William Brown when I was younger, and I borrowed this compilation of short stories recently. It's quite an old book, published originally in the 1930s.
All of the stories were very funny, but the highlight of this book is definitely the second story, "William Holds the Stage", starting with a hilarious sequence involving William learning that some people believe that Shakespeare's plays were written by Francis Bacon and ending up with him disrupting a production of Hamlet.
There are a lot of William books, and I probably ought to read more.