10oz Mug reveal book titles rare out of print for book lovers!

I got this mug as a gift. I figured out, I will sell it because I just got another one almost the same. Check this out: * 1st photo mug is as is *2nd photo when hot drink is put will uncover the words that are covered and actually book titles of bestselling books! Like new condition Hand wash only. Makes a perfect gift for a book lover or a librarian! Offers welcome.