They slip

Running across soaking wet mud is never a good idea. With another click of your fingers you watch as the girl stumbles in her running, crashing into the boy and both of them collapsing into a huge muddy puddle.

The girl screams, fighting to get back to her feet, asking how the hell the mud had grown so wet so quickly, but she slips again, sending the two of them sprawling once more.

When they finally managed to fight their way to their feet both are covered head to toe in wet mud. "What is the meaning of this?"

Both look to the source of the voice and they see Miss Nolan - the schools assistant principle - stalking towards them. "Simon? Jenny?"

"We were caught in the sprinkler Miss." Simon explains. "And then we tripped..."

Miss Nolan stares at both of them for a moment. "If that's true then you must be the unluckiest students in the school." She finally says. "Inside, and shower now, the pair of you."