Perm him
A good stupefy, and a trip to the ever-useful room of requirement, and Snape's hair was ready… even if they had had to use levitation spells instead of touching the greasy black strands. Finally, the still-unconscious Slytherin teen was deposited in their potions classroom, ready to be found later.
Severus awoke, to find himself in the dimly-lit but comfortably familiar potions classroom.
At least, it would have been comforting if he had known why on earth he was there. It was a Saturday, so it's not like he could have just fallen asleep in class or something. That and even the idea of Severus Snape falling asleep in a class (History of Magic doesn't count) was ludicrous. So, there was clearly some other reason he was here. Severus thought back to before he had awoken. He recalled leaving the Great Hall after lunch with Nott, then Nott had gone to the library while he… he had been going back to the Slytherin common room, when all of a sudden he had fallen down. So why was he here?
Rather bemused, Severus got up to leave. On his way out of the room, however, he caught his reflection in a brightly polished cauldron, situated on the wall. He did a double-take, then stared in mild horror at the dark-eyed boy staring back at him, pale face surrounded by large, wavy hair.