A firm I know of lacks integrity and has pulled all types of dirty stunts on their competitors. One of their competitors paid the floor above them a visit during a customer reception they were holding.
Several people stuffed the toilets full of newspaper and toilet paper, then flushed all 12 toilets at the same time.
The resultant flood on the floor above caused several ceilings to cave in and generally ruined what had been a great party.
A few other dirty tricks were pulled on that firm but they had it coming. They got the idea when it started costing them customers and money.