From Wiktionary, the free dictionary
From shout + -fest.
shoutfest (plural shoutfests)
- (informal) An event characterized by shouting.
2009 July 11, Jon Caramanica, “The New-Old Country of 3 Pixies From Dixie”, in New York Times[1]:At the encore, “Fun Stix Party” devolved into a raucous, peppy shoutfest that was also the most technically flamboyant song of the night.