In second year they had spent their weekends creating a charm of disillusionment to cast over their regular clothes so it looked like they were wearing their school robes and vise versa. This charm was excellent for the first day of school when they caught the Hogwarts Express, instead of changing into their robes in the cramped co-ed carriages the boys were able to wave their wands over themselves, the spell rippled out of existence switching their muggle attire to school uniforms. The only problem was they needed someone else to cast the spell initially as they were still underage. However, Draco had an easy answer to that. 