The sound of disgust coming from a crowd at a sporting event after something they didn't like happens.
The sports announcers reported, "That questionable call by the officials brings out the 'Boo Birds'."
by ChrisDoc November 10, 2009
Get the boo birdsmug. Home team fans at a sporting event who boos one or more members of the home team because of the team playing bad.
by stanley2toronto September 28, 2011
Get the boo birdsmug.