I was getting into an elevator and the doors were closing. A hand comes through to keep the doors open enough to get on the elevator. The guy gets on the elevator and I almost said "I hope you didn't need that hand" and guess what. The other hand was a chrome hook.

This is a true story. It was more humility and bite your tongue.

One summer at the beach a girl was really rude to me,I was hurt and really upset. I was there with my sister, but she was with a big group of young people, and they were having such fun. I wished deeply I had her life. Fate had it that the next summer I was there with that big group of friends, with a new boyfriend who happened to be her ex! and she was standing alone somewhere wishing to make it back to the group.Karma yes? It was all coincidence, I met that guy in winter, and turned out his ex girlfriend who had cheated on him with a friend of his was her after all.

this isn't my story, its my mothers, i first heard about it a few days ago, and i think it fits here.

my mother used to work at me n eds before i was born, and there was a girl there that would be really annoying, who i will be calling jenny
one day, my mother had made a mini pizza for herself to eat, and was going to eat it when she had to answer the phone to take a order, so she grabbed her mini pizza and put it next to her as she took the order.
as she was taking the order, she saw out of the corner of her eye, jenny walking up next to my mom, and grabbing the cheese off of my moms mini pizza and gobbling it up. my mother went up to jenny and asked her if she really just did that, to which jenny then said "yup! and it was DE-LICIOUS!". my mom, who at this point has had enough of jenny, grabbed what was left of the pizza and smashed it into jenny's face.
jenny later complained to the manager, and according to my mom, the manager had asked why jenny even stole my moms pizza, to which jenny said "because it was just there, and i wanted it!". jenny got in trouble after that haha

i was very surprised when i heard this story a few days ago, because i didn't think my mother was the type to do this to someone who took her pizza, but i guess she is. or maybe she was just hangry, who knows

Maybe not so much karma as an I told you so, but my oldest was having problems with someone and was told to avoid them. Her mother and I told her that she should not go to X place and just stay home, but she threw a fit and went anyway. She got her phone stolen out of her hand...