A book you've read more than three times.
As embarrassed as I am to admit it, Twilight is the only book I have read more than 3 times.
I was 15 and impressionable, I couldn't get enough of Edward and Bella's relationship.
Unfortunately now I have so many books I want to read, it's difficult to find the time to re-read beloved books. TFIOS is one of those books I will keep going back to I think, it's too good for words.