I would also mess with the songs and turn down the sound on boring or plain stupid people...
But i would also printout funny cartoons or parody bits from this forum and leave them accidentally around the hall...
eg, the memorial invites parodies from last year! I printed out heaps of the funny ones (perhaps someone can post the link to that thread here...i dont know how to) Then i would trim them to the same exact size, and slip them in amongst the real invites! so many got distributed in the community!