OK fellow Halo fans!  

Here is the lesson of the day.

How to conduct yourself in someone else's stadium:

1. Feel free to wear your colors, but be prepared for the fury.
2. Never, ever engage an "enemy" fan; do not even give them the satisfaction of eye contact.  Never speak directly to them.  Only speak your actions toward the field and the players on your team (yelling something offensive to their players' team is not right either).
3. Clap, but not too loudly, if your team makes a great play.  If it is a game-breaker for the enemy, do not clap at all and just soak it up, internally.  Wait until you are back in your car to scream with joy.
4. Never turn around, unless the big screen is behind you, no matter what is raining down on you.  If the projectiles keep coming, save them and bring them to the nearest security personnel.
5. If people push you while walking around the concourses, just ignore it.  Don't ever engage!
6. Do not ever turn around after your team made a great play to rub it in on them.  Too many times, I have seen idiot fans of other teams jumping up on their seat yelling in my stadium.  Not cool.  When my team wins in their stadium, I stand, clap, and stare directly onto the field and at my team's players!
7. Minimize your alcohol consumption while in "their house."  A clear head will always prevail in a hostile situation.
8. Be conscious of the other team's history and their successes against your team.  Wow the "enemy" fans with your distinct knowledge of their team, their traditions, and their victories.  Keep track of their lowest points, too, so you can have a retort to them beating on your team too bad, if necessary.
9. If your team wins, be happy, but do not gloat or run through yelling "woo hoo!" or anything like that.  Just walk with the crowd, soak up the glory of being surrounded by enemies who are in pain.  It's a nice feeling.  Sometimes, they end up beating each other up over dumb stuff like "who's been a fan longer than the other guy."  Comedy.
10. If your team loses, take the stupid comments and keep your hands open (don't think of making a fist) and don't make any eye contact.  There will be a lot more smack spoken when your team loses, but that is part of losing in "their house."  Take it and be a man about it.  Walk to the car quietly, maybe making a few comments with your friends about the one or two good plays your team made during the game.

I have followed these rules several times in enemy stadiums and have never had a problem.  Never.  Just a little bit of spit, hot dogs and coins drilled into the back of my head, but ignore those drunk idiots.  If they see that you are riled up, they will escalate and continue to ride you.  If you ignore it, you have defused the situation.