Heh! Many years ago an ex-colleague of mine (Hi Stuart) was summoned by the fire brigade to come in and unlock/inspect the machine room in our office due to the fire alarm going off at the weekend.
On arrival, there were no signs of conflagration; however, careful inspection revealed that under the suspended floor there was a pool of water which had shorted out the alarm relays, and was lapping gently at the 3 phase supply to the machines. Turned out that the cleaners were in the habit of stuffing a spare bog roll into the syphon traps in the cistern overflows in the toilets, and that one of same had actually overflowed over the weekend, causing the bog roll to expand massively, block the outlet and start a steady trickle of water running to the lowest point in the building. If anyone can beat "swollen bog roll" as a reason for a callout, I'd like to hear it.