"From now on, one Chaser will attempt to beat the Keeper, as opposed to three Chasers beating the Keeper up."
-- Ministry spokesperson (QA6)
It recorded the introduction of a new rule outlawing more than one Chaser at a time entering the scoring area, which would now draw a foul and penalty. Quidditch fans were extremely unhappy with the Department of Magical Games and Sports at this ban of the much-loved and traditional match tactic known as “Stooging” (QA6).
Lexicon list of Fouls
From the Web
Writing by J K Rowling on Pottermore: The Daily Prophet
Pottermore feature: Quidditch collection
Harry Potter Wiki: Stooging