I was talking to my mentor about my attempt to contact Six Flags, and he mentioned people will have to pay to get in. If they give me a group rate, I can increase that for people and then use that to make money for the charity. I also talked to a kid that worked there, and he mentioned they already have stuff happen where I would want to do the mob, so that means the area is a safe place to use, and I know the park has a sound system.
Someone was trying to sell Northern Quidditch shirts in lunch today, which gave me an awesome idea. When we're in Harry Potter World in Universal, have possibly a mini flash mob there with the shirts. Maybe a bunch of 'duels' between people all in a huge battle right in the middle of the place?