I think quite fun and rewarding. As I walk down a street, I commit something of a cultural no-no by making eye contact and smiling at a passing stranger. I love to see what happens. Often, I have a goal of seeing how many smiles I can collect in the time it takes me to walk to my destination. Seeing what happens is the fun part.
Some people completely close down in fear and walk past more quickly.
Others will receive my smile, get flustered, lower their eyes and walk faster, but often with a tiny smile on their lips. Usually, we will both pass along more smiles as we go on our respective ways. Take a little smile and pass it on. Increase the joy in your life. Take a smile and pass it on.