If you don't expect any credit or reward for your behavior and genuinely want to help out someone you don't know, you definitely have some good karma coming to you. Paying for a fellow grocery store customer who is struggling, helping someone with their bags in an airport, or just seeing that someone needs help and going out of your way to make sure they get what they need can also give you a story whenever you need some faith in humanity.
So, when a Reddit user asked, "What's the coolest thing you've done for a total stranger?" people who have earned their adult scout badges were ready to share. There are good people out there, rejoice!
I made a bouquet of (about fifteen) roses for my (then) girlfriend for Valentines' day (I grow roses). I was sitting on the bus across from this girl that was about three years younger than me. I sat down, put the vase of roses on the seat next to me and prepared to send me girlfriend a text message.
Then I heard her. Bawling her eyes out. The girl across from me had seen the flowers and (I'm guessing) had broken up with her boyfriend a few days prior, and just started crying. When my stop came, I gathered four roses from my bouquet and said "Look, these were for my girlfriend, but you look like you could use a few. Happy Valentines Day!" and handed her four roses.
The anonymous girl grinned from ear to ear and let out a sheepish "Thank you...". I smiled back, turn 'round and got off the bus. - mordicaii