Back in the 1970's & early 1980's, I would see big mouth Boston Red Sox fans running their mouths at old Yankee Stadium. I would think, "Keep it up, and you'll be sorry!" After all, they were on our turf, and they were greatly outnumbered. Sometimes they were pelted by flying beer cans.
During the 1976 World Series ( I had tickets for 3 home games), when my Yankees were swept 4 straight by the Big Red Machine (Cinncinnati Reds). There was a big mouth Reds fan running his big mouth. The Yankees were losing, so they were in no mood to listen to a loud mouth. So a lot of Yankees fans ganged up on him verbally and trashed him. Later in the game, I saw police usher out a fan who was bleeding from one of his arms. Don't know who he was rooting for, or if he was the loud mouth or not.