One day in their fifth year, the Weasley twins had a fantastic, exciting idea. They had been able to trick almost every Professor in Hogwarts over the years, except for one. Professor Snape. That man was always one step ahead; he seemed to know things before they happened. It was strange, he seemed to have the uncanny ability to read minds. However, the twins noticed that, as of late, their Potions Professor had been rushing about the castle, black robes swirling around him, barely watching where he was walking. His mind always seemed to be someplace else. He seemed distracted, and a distracted person made an easier target.
During their Potions lesson one morning, Fred very quietly said "How funny would it be if one day he tripped? The dungeons bat, not so graceful anymore!" George chuckled and responded, "Great idea! Not a bad fall, but just enough to make his pride take a dip." They laughed, and the idea was set in motion. Instead of writing out the Potion they were supposed to be copying from the board, they formulated their plan. They would simply use some string, one of the Hogwarts elves could easily get that for them under the pretence of hanging some posters up in the Gryffindor common room. They would hang the sting across the walkway in the Charm corridor, and cast a disillusionment charm on it. Neither thought the Professor would fall; he was too keenly aware of that… or so the twins told themselves. At lunch, they set the date and time of the event and spread the word around the school. Students were eagerly waiting for the following Monday. Only a couple of students disapproved. Hermione Granger, for one, but that was to be expected - she always was the teacher's pet.