Now we all have heard or used the excuse "The dog ate my homework." when we were growing up from first grade on. I've even heard some people try to use it in the college years. But until my wife worked at a book store I never heard of people using it outside of a school setting.
My wife has worked in several retail stores, some of which were book stores. Every year after Christmas she would come home with some really funny stories about what some customer had to try and get their money back or have their item replaced.
The one I will most likely till the day I die though is this. While working at the register one day a nice looking middle aged woman came into the store when she got to the counter she pulled a book out of her handbag that clearly had been damaged and said "I bought this book earlier today then when I got home my dog used it as a chew toy. So I want my money back."