"Me and me dad like watching them Keepers flattened."
-- a young Quidditch fan to the Daily Prophet in June 1884 (QA6)
It was outlawed and declared a foul in 1884, due to the number and severity of injuries to Keepers, and a penalty is now awarded to the opposing team. The Daily Prophet article published on 22 June 1884 “Our Chasers Aren’t Cheating” describes the uproar when this decision was announced (QA6).
The word stooging (Engl) has been used to mean (1) drifting aimlessly and (2) performing the role of being the butt of a comedian's jokes (Oxford English Dictionary). The Quidditch usage provides a new third meaning.
From the Web
Writing by J.K. Rowling on Pottermore:
Pottermore feature: Quidditch collection
Harry Potter Wiki: Stooging