Leave a surprise note in a library book.
Kindness sneak attack! Here’s a great RAK if you’re shy or looking to surprise someone with your same taste in literature.
Slipping a dollar bookmark in between the pages is an easy option, though there are tons of free routes to pursue as well. Write a positive message or draw a picture. Even something as simple as “You are awesome and I hope you have a fantastic day!” will be appreciated by a stranger.