Literary crack refers to books that are very, very addicting. While some claim to have fallen victim to LC from reading Harry Potter, the truest occurrence of LC is found from reading Twilight.
Just like crack, literary crack will screw your mind over in the end. Trust me, I suffer from it (from Twilight), and it's horrible. All you think about is the book, characters from the book, what the characters do in the book, ect. Basically, it consumes you.
From my own experiences, literary crack users need to read their book of choice at least once a week. They constantly quote the book, too. Fansites about the book are usually where they are, and they are very picky about details when it comes to the book.
If the book happens to be made into a movie, they love to spend their time criticizing the actors, released clips, and photographs. They won't enjoy the movie when it is released, and will complain about cut lines/scenes and added lines/scenes. After all, people on LC do know the book the best.
In serious cases of extreme LC use, they begin to have no life, and instead take it upon themselves to become someone from the book.
Although it may seem horrible to you, LC users are quite happy. It is only until the last book is released, that they go into a mental breakdown.
I've supplied literary crack to three people.
Twilight has dazzled girls across America, with each one spreading the literary crack to their friends.
A series novel which is poorly written and follows some formulaic structure which may or may not be predictable. Despite knowing that it sucks the reader will become addicted to the series and burn through every book as fast as possible.
If the next book in the series is unavailable the reader will go through withdraw like symptoms until the next book's release date wherein the reader will wrestle and scream and claw their way to the register to purchase said book.
I know that it's bad for me but "Twilight" is my literary crack, I can't help it!