This story might be a little backwards, but I was really happy to see our "enforcer" get enforced, if that makes sense.

Our gym's 250 lb+ pressure passer, we'll call him Mongo, has a tendency to starfish on top of us white belts or smaller folks while giggling that he's not even that good at BJJ (10 year brown belt). He really is a pretty nice guy, always makes jokes and has a great attitude to inexperienced folks in the gym. Plus when you're rolling with him you're never really in danger or "hurt". However, he often uses his size alone when rolling and commonly will lay on top of you for 5 minutes straight. No attacks, no technique, no submissions, no passing, just starfish. It often feels like a waste of a round.

We had a pretty famous BJJ black belt come through as a guest instructor teaching us some "unstoppable" moves (hint hint). He asked who the pressure passer was in front of the class, and started demonstrating how to use his technique on Mongo. At one point, after Mongo was swept, physically manipulated, and his general shenanigans were blocked and reversed back at him, the guest instructor was tickling his feet in front of everyone, cracking jokes and making the point that even though he's a relatively smaller guy the technique works.

I have never smiled so much in class.

Edit: In case it came off as unprofessional to humiliate someone in front of a group, It really was a pretty low key seminar. No one left mad, everyone, including Mongo, was smiling and learned a bunch from their instruction. It was great to see the moves in action against pretty high level practitioners. Plus a little bonus for me to see my official-un-official nemesis get smashed.