‘Transfiguration is some of the most complex and dangerous magic you will learn at Hogwarts,’ she said. ‘Anyone messing around in my class will leave and not come back. You have been warned.’ Then she changed her desk into a pig and back again. They were all very impressed and couldn’t wait to get started, but soon realised they weren’t going to be changing the furniture into animals for a long time. After making a lot of complicated notes, they were each given a match and started trying to turn it into a needle. By the end of the lesson, only Hermione Granger had made any difference to her match; Professor McGonagall showed the class how it had gone all silver and pointy and gave Hermione a rare smile. mess around - to behave in a silly and annoying way, especially instead of doing something useful: 'I messed around in my first year at college.'