Quote from : Harry Potter and the Half-Blood Prince Book

Ron seems to be enjoying the celebrations.” said Hermione. “Don’t pretend you didn’t see him. He wasn’t exactly hiding it, was — ?” The door behind them burst open. To Harry’s horror, Ron came in, laughing, pulling Lavender by the hand. “Oh,” he said, drawing up short at the sight of Harry and Hermione. “Oops!” said Lavender, and she backed out of the room, giggling. There was a horrible, swelling, billowing silence. Hermione was staring at Ron, who refused to look at her. She walked very slowly and erectly toward the door. Harry glanced at Ron, who was looking relieved that nothing worse had happened. “ ” came a shriek from the doorway. Harry spun around [...] The little flock of birds was speeding like a hail of fat golden bullets toward Ron, pecking and clawing at every bit of flesh they could reach. “Gerremoffme!” he yelled, but with one last look of vindictive fury, Hermione wrenched open the door and disappeared through it. Harry thought he heard a sob before it slammed.