The best comparable story I remember to this was when the Eaton Centre in Toronto (one of the largest shopping malls in the city, right down town) was shut for a couple of hours because of a carton of milk.

"Milk" was running a contest where your carton of milk would "Moooo" when you opened it if you were a winner. There was a small electronic gadget inside the carton that when opened would sound a moo. Someone in a foodcourt had a carton with this device in it and they had just left it on the table of the foodcourt when they left. A passer-by saw the carton had wires in it and called security. The whole south end of the mall was evactuated while the bombsquad came and determined the relative threat level. Cracks me up just remembering it...