Denise Valtr

“Oh it was my pleasure, dears,” said Mrs. Weasley. “I’d invite you for Christmas, but … well, I expect you’re all going to want to stay at Hogwarts, what with … one thing and another.” “Mum!” said Ron irritably. “What d’you three know that we don’t?” “You’ll find out this evening, I expect,” said Mrs. Weasley, smiling. “It’s going to be very exciting — mind you, I’m very glad they’ve changed the rules —” “What rules?” said Harry, Ron, Fred, and George together. “I’m sure Professor Dumbledore will tell you. … Now, behave, won’t you? Won’t you, Fred? And you, George?” The pistons hissed loudly and the train began to move. “Tell us what’s happening at Hogwarts!” Fred bellowed out of the window as Mrs. Weasley, Bill, and Charlie sped away from them. “What rules are they changing?” But Mrs. Weasley only smiled and waved.”
― J.K. Rowling, Harry Potter and the Goblet of Fire

“We won't be seeing you,' Fred told Professor Umbridge, swinging his leg over his broomstick.

'Yeah, don't bother to keep in touch,' said George, mounting his own.

Fred looked around at the assembled students, and at the silent, watchful crowd. 'If anyone fancies buying a Portable Swamp, as demonstrated upstairs, come to number ninety-three, Diagon Alley — Weasleys' Wizard Wheezes,' he said in a loud voice, 'Our new premises!'

'Special discounts to Hogwarts students who swear they're going to use our products to get rid of this old bat,' added George, pointing at Professor Umbridge.

'STOP THEM!' shrieked Umbridge, but it was too late. As the Inquisitorial Squad closed in, Fred and George kicked off from the floor, shooting fifteen feet into the air, the iron peg swinging dangerously below. Fred looked across the hall at the poltergeist bobbing on his level above the crowd.

'Give her hell from us, Peeves.'

And Peeves, who Harry had never seen take an order from a student before, swept his belled hat from his head and sprang to a salute as Fred and George wheeled about to tumultuous applause from the students below and sped out of the open front doors into the glorious sunset.”
― J.K. Rowling, Harry Potter and the Order of the Phoenix

“A week after Fred and George's departure, Harry witnessed Professor McGonagall walking right past Peeves, who was determinedly loosening a crystal chandelier, and could have sworn he heard her tell the poltergeist out of the corner of her mouth, "It unscrews the other way.”
― J.K. Rowling, Harry Potter and the Order of the Phoenix

“Are you trying to weasel out of showing us any of this stuff?' said Zacharias Smith.
'Here's an idea,' said Ron loudly, 'why don't you shut your mouth?'
'Well, we've all turned up to learn from him, and now he's telling us he can't really do any of it,' he said.
'That's not what he said,' said Fred Weasley.
'Would you like us to clean out your ears for you?' inquired George, pulling a long and lethal-looking metal instrument from inside one of the Zonko's bags.
'Or any part of your body, really, we're not fussy where we stick this,' said Fred.”
― J.K. Rowling, Harry Potter and the Order of the Phoenix