Why was the book angus thongs and full-frontal snogging banned and challenged?

This book, while being widely considered as a very good read, can raise some problems. The main character is a 14-year-old girl (Georgia) and much of the book deals with her encounters with boys. Some of this includes kissing, 'making-out', and several 'groping' encounters. These areas of the book are considered by some to be inappropriate, perhaps condoning behavior that they do not wish their children to engage in. There are also references to lesbianism, erections, and pornography.

Georgia is also a bit of trouble maker at school, and though she clearly loves her family, she is very flippant/sarcastic/etc with her parents.