Explain that as a social experiment, through the audience booking tickets you have all their banking information and that
someof their details have been used to access child porn on the net, around 10 random people in the room potentially face charges of paedophilia.
Say that statistics dictate that in an audience of this size, it is likely that two people in the room are likely to be real paedophiles. Then say that the two in the room have 30 minutes to make themselves know to the audience and face prosecution or the police will be notified that 10 people in the room have accessed illicit photographs of children.
Then just sit back on a chair on stage and start a 30 minute countdown, with performers dressed as security at the exits.

I feel devilishly creative
Reckon that would do it.