One day, after he spent the night tossing and turning in fits of guilty rage, (he didn't want to become a death eater like everybody presumed.) Draco Malfoy woke up to find him self turned in to a giant cockroach.
It was a strange turn of events, one that he can't have seen coming. He assumed there was some sort of Dark Magic involved, obviously by Voldemort to scare him into submission. It was not possible that the golden trio did it, because they were obviously too stupid, too heroic and too ugly to think of anything like this.
He found himself on his back and could not get on to the floor because of the anatomical considerations of the average cockroach.
Blaise Zabini walked in to the seventh year boys dorms, and pushed Draco on to his legs, as if it were the most normal thing in the world.
Draco then scuttled to Professor Dumbledore's office where he proceeded to tell the principal what happened.
After a through examination, he concluded that there was nothing wrong, except the fact he was a giant cockroach. No magic was involved.
Ultimately, Draco was forced to live an unfulfilling life as the only resident giant Cockroach in Hogwarts.
But at least he didn't have to beome a death eater. Voldemort HATED arthropods…