[Mr. Pickles]

Bring along a rookie and give them a flash unit. All they have to do is look for the offenders. When they see an offender getting ready to take a shot, and if they have a P&S camera, even better, have your rookie put the flash. Overexposure for sure.

Or tell the B&G several times before the event, and give them a print discount if they are successful in getting the "message" to their guests.