Irish get drunk and start punching each other

The only fighting scene I can think of in this film was the one that took place at the end, which was initiated by the American character.

"The guy we're meeting with can't even grow his own hair?!? COME ON!!!" -Gob

Well, and I am half Irish, it is what they do.

Tis what they do on a Saturday night, an' if ye haven't had a fight, ye haven't had a good night out!