As a favor to new Cubs Carlos Pena, Matt Garza, Fernando Perez, and returning fan favorites Kerry Wood and Reed Johnson, I thought you'd like to know the rules. They aren't all that complicated, nor do they make a lot of sense, but they are undeniable and unforgiving. These 10 things, you simply cannot do and expect to be accepted by the Greatest Fans in the World ™.
10. Show too much emotion.
9. Show too little emotion.
8. Get injured.
7. Play while injured and make your injury worse.
6. Play while injured and try to avoid making your injury worse.
5. Miss time due to injury.
4. Put off surgery too long.
3. Accept a no-trade clause much less invoke it.
2. Have dinner.
1. Under any circumstances point out that any of this is the slightest bit silly or that the Greatest Fans in the World ™ include temperamental, irrational, racist, ignorant, or otherwise mercurial members among their ranks.
Just don't do any of that and also play awesome, and this town will love you to pieces!