“What’s the matter?” said Harry.
“She’s — she’s sent me a Howler,” said Ron faintly.
“You’d better open it, Ron,” said Neville in a timid whisper. “It’ll be worse if you don’t. My gran sent me one once, and I ignored it and” — he gulped — “it was horrible.”

Harry Potter and the Chamber of Secrets - Chapter 6 : Gilderoy Lockhart
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