From the urban legends about celebrities category: When Life, the Universe, and Everything came out, my cousin went to get his girlfriend an autographed copy from a book store in Oregon.

When he got to the table he saw Douglas Adams seated next to a pyramid of beer cans about 2 feet high. Apparently Adams had cut a deal with the store. His appearance fee wasn't money, it was all the beer he could drink.

Adams signed the book below the inscription "This book has just been defaced by the author."