Joanna Tipling was the school bitch. Taller, better looking and more well endowed than most of the other girls, she was a spiteful mare who valued no-one, abused everyone and (most importantly) knew everyone looked up to her, be it the girls who wanted to be her or the jocks who wanted to be in her...
Rachel hatched a plan on the way to school - all she had to do was sneak some chocolate into Joanna's food somehow and sit back and enjoy the fireworks.
The opportunity presented itself quickly enough - whilst following Joanna through a corridor, paying attention to hold back and not draw attention, she noticed Jo leave her satchel on the wall before joining her friends in the toilets.
Swiftly sneaking over, Rachel broke up some chocolate and distributed it amongst the witches lunch.
"Here goes nothing..." she thought, quickly leaving the scene as the girls re-emerged.
"I wonder what's going to happen..." thought Rachel, "I just grabbed a random chocolate from the box!"