During our first days at high school we discovered that just outside behind the toilets there was a tap in the ground that allowed you to turn off the water to the girls toilets. We immediately turned it off much to the annoyance of many girls who could no longer wet their hair to make them look "sophisticated". Eventually some girls we were friendly with wished to use the facilities so we re-enabled their water privileges. Just us as we were turning the water off again once they were done, the janitor walks up and just stands there looking at Max lying on the ground with his arm down the hole. He quickly stammered "err... someone turned the water off, so we were turning it back on."
"I know exactly what you are doing." says janitor.
We didn't get in any trouble but two days later they sealed up all the tapholes around the school. It seemed we would have to find another way of extorting people out of their lunch money.