When I was in 7th grade, two 8th grade girls always made fun of me, and were generally really mean to me.

One of them moved away, and i never saw her again, but When the other graduated that year (from jr high to high school), I bought her a box of chocolates. She cried her eyes out and apologized for being a jerk, and we became friends.

A guy I went to h**h-school with "friended" me on Facebook. He was caught stealing from my house once back then, bragging about it to mutual friends (whom he thought would not tell me). After the incident we never spoke, although we had the same circle of friends, I kept my distance, he kept his.

Flash forward 20 years to now and we were "friends" on Facebook. I have a pretty cool job in the music industry, good money and I travel the world. I usually add these former "friends" just so they can see my life turned out pretty awesome while most of them are in our old home town working s**t jobs...anyway.

He updated his status saying that he was devastated that someone stole something from his son and karma this, blah blah blah. Amongst all the posts from his friends being sorry for him, I simply wrote something like "Yeah, its really terrible when someone steals from you eh? That must really suck. Karma does have its way of evening things out though." I immediately started getting PMs from mutual friends congratulating me, who remembered the incident in school. He "un-friended" me after that to my extreme pleasure.

TL/DR Karma eventually 20 yrs later.