Wikia

Dean: "Send him off, ref! Red Card!"

Ron: "What are you talking about, Dean?"

Dean: "Red card! In football you get shown the red card and you're out of the game!"

Ron: "But this isn't football, Dean."

— Ron explains that this isn't used in Quidditch.^[src]

The red card is a tiny object used in the Muggle world in football matches. In 1991 Dean Thomas yelled that one of the Quidditch players on Slytherin Quidditch team should be given a red card for knocking out Harry Potter. Ron Weasley told him that such an object doesn't exist.^[1]

Behind the scenesEdit

During the filming of the Harry Potter films, actors who misbehaved were said to receive a "red card." Actress Emma Watson received her first red card of the series due to inappropriate laughter during her scenes with Rhys Ifans in Harry Potter and the Deathly Hallows: Part 1. She was initially annoyed, as she was the "class pet," but later accepted it as "It would be a little bit sickening if I hadn't gotten a single one, so, fair enough."^[2]