Specifically, I trolled a Minecraft grief team. Groups of griefers often use a phrase to identify each other during organized grief sessions. I have actually exploited this once to troll an entire grief team to the point their forum's most active thread was about me. It was hilarious. What I did was sign up on the grief team website, and pretended to be a griefer until I was able to view the organized griefs of the group. Note that not once did I give out my actual IGN to this group (that would have ruined it). I went into servers the griefers planned to grief, and gave the admins evidence of their "secret" phrase. Now comes the best part. The griefers join the server, say the phrase or some variant of it, then get immediately banned. I did it on a few targeted servers, and soon enough most of the grief team went ranting on their forums. It actually ended up causing them to start to fall apart as they all started questioning who was loyal to the group or not. Eventually, the group seemed to just disappear.
TL;DR: I trolled a Minecraft grief team to the point they kinda fell apart.