It's usually because they play music and only have like 1 crappy speaker, so they have to blast sound out of that speaker, and anyone nearby has to scream to ha

It's usually because they play music and only have like 1 crappy speaker, so they have to blast sound out of that speaker, and anyone nearby has to scream to have a conversation over the speaker, and then anyone near that group has to scream even louder, and before you know it - everyone is screaming and you can't even hear the music.