When I was working at Macdonalds we had an old employee that did a load of stuff before he left. There was a false celing upstairs and he managed to fill it almost full of rubish from the bins over the course of about a week. There was fish portions put on top of the light fittings and bags of frozen nuggets put into lots of filing cabinets in the office. The place smelt rather bad for a while after we discovered what he had done but looking back on it was funny as hell then.