Actually, from my experiance, American Football isn't all that different.
I come from a family of diehard Giants fans.
I've gone to a couple games with my dad back in the day. Then again, because we have season tickets, everyone with us is obsessed with football. A couple of the men are downright nasty to the other teams, for a lack of appropriate terms. I'm not sure about the rest of the stadium, because we always sit in the same section.
However, knives aren't allowed to be brought into the stadium.