I'll share one of my experiences.

This happened a few years ago. It was Super Bowl time and one of my friend tells me he's having a party. I'm not really a football fan and don't know anything about the sport but I agree to go cause I'll occasionally watch the Super Bowl and I've been to a few parties over the years and they can be fun.

On my way to the party I stop to pick up some beers and some chips. The total wasn't much but I only had a $100 dollar bill on me so I paid with that. After receiving my change I quickly notice that the cashier gave me $20 extra. Without thinking twice I tell her that she gave me too much and hand the $20 back to her. She was legitimately shocked and thanked me profusely. I told her not to worry about it, I know what it's like to deal with a register and how you're responsible for your till at the end of your shift and if there was an error made and it's short it's on you.

I get to the party and the games going to start in about an hour or so. My friend greets me and tells me they are placing bets for the game. I tell him I don't know anything about the teams or really football in general. But, in the spirit of the party I say I'll put in $10 if he does all the details and places the bet for me. He agrees. My bet ends up being the winning bet that night! My $10 turned into an easy $500.

I couldn't help but think maybe that was karma coming back to me for the $20 I gave back.