Fictional sport in the "Harry Potter" series which is played on flying broomsticks

"See ya!"3 Fourth of July cookout, for short3 "It's ___ lucky day!" (what a salesman may tell you?)4 Scary-sounding Great Lake4 Brit's restroom, informally3 Hawaiian floral garland that may have hibiscuses3 Breakfast grains that may be rolled4 Another name for a killer whale4