To blurt is to say quickly whatever comes first into your head (Oxford English Dictionary).
During the play-off match to determine the third place finish at the Quidditch World Cup in 2014, the brooms of US teammates Darius Smackhammer and Lucas Piquery were locked together due to the flying skills of Japan's Seeker, Noriko Sato. It was not considered to be a foul because they were on the same team (Pm).
Lexicon list of Quidditch fouls
From the Web
Writing by J.K. Rowling on Pottermore: 2014 Quidditch World Cup reports
Pottermore feature: Quidditch collection
Harry Potter Wiki: Blurting