Wish I was in this session

Check out this great idea Jeffrey Cufaude used in a recent session he led at ASAE and The Center's Great Ideas Conference:

I had the 60+ people in my session on Beyond Brainstorming: Facilitation Tips and Techniques for Generating Great Ideas crumple a sheet of paper into a snowball and pelt me with it when they got a good takeaway from the session.

Being trashed in public has never been so satisfying.

Why does that sort of thing never happen in sessions I go to?