People get away with enough terrible things in this world to make it a little hard to believe in the concept of karma sometimes, so it becomes incredibly satisfying when someone really does get what's coming to them.
If what goes around comes around, it usually happens over a longer period. But for these people, karma struck immediately after their act of foolishness.
1. Taxi driver's revenge
2. Payback
3. Following the clues
4. Taught a lesson
5. Sibling rivalry
6. Flying too close to the sun
7. When you leave a dog in a car for too long
8. Justice for the thief
9. Instant karma
10. Taste of their own medicine
11. Shortcut gone wrong
12. Well that backfired
You can imagine with most of these, the culprit really thought that they would get away with their misdeed with no consequences whatsoever. Hopefully a little dose of karma woke them up to the real world a little bit.