Water Fight

In the dorm, one of the favorite intramural sports was
water fights.
Dousing and bombarding one another with water from
squirt guns, glasses, balloons, even wastebaskets. Since
each room had a sink, there was endless ammunition. The
most frequent target was the resident assistant.
Approaching his room one afternoon, he noticed his door
was ajar. Looking up, he saw a pail of water balanced on
the door's edge, ready to fall on him. As he took down
the pail and emptied it into his sink, he thought, Those
crazy guys actually thought they could fool me with that
old gag! It was then he realized that "those crazy guys"
had removed the drainpipe beneath the sink.