GTA Online: Passive Vigilante trolling
It's amazing how you can get other people killed using a rocket booster and some random NPC cars.
There's several things that make this really fun because it doesn't count as you killing the other person:
1. No insurance
2. No badsport
3. You aren't forced out of passive mode when you get someone killed
4. The other person isn't told who or what killed them
5. The other person can't passive ghost to you
Also, because you will usually have at least two stars, anyone shooting at you in passive will instantly get a wanted level and have cops trying to kill them.