What do you do when you don't like a book?

I am curious as you may know;-), therefore I am interested to know what you are doing when you read a book you don't like.
Do you still read it till the last page, hoping that the story will become better?
Or do you give up and start a new book? If you give up, after how many pages do you do it?

Personally I give up when the 50-70 first pages do not suit my taste. Therefore I started a new book, after having spent some boring time with a book from Binnie Kirshenbaum...