“As though an invisible hand were writing upon it, words appeared on the smooth surface of the map. "Mr. Moony presents his compliments to Professor Snape, and begs him to keep his abnormally large nose out of other people's business."
Snape froze. Harry stared, dumbstruck, at the message. But the map didn't stop there. More writing was appearing beneath the first.
"Mr. Prongs agrees with Mr. Moony, and would like to add that Professor Snape is an ugly git."
It would have been funny if the situation hadn't been so serious. And there was more...
"Mr. Padfoot would like to register his astonishment that an idiot like that ever became a professor."
Harry closed his eyes in horror. When he'd opened them, the map had had its last word.
"Mr. Wormtail bids Professor Snape good day, and advises him to wash his hair, the slimeball."”