So you're thinking of going to Germany for the World Cup? Fabulous! If you'd like advice on how to behave, here's an archive of tips written by foreign residents of Germany for you, courtesy of the Spiegel magazine.
As a World Cup tourist from some underdeveloped region of the world, you should know: not all Germans are Nazis, some of them just want to make a nice profit from you. Nonetheless: there are also tourist traps in Germany, and plenty of behaviors you're better off avoiding:
Blathering on pointlessly
In Germany, communication is always goal-oriented ("Out of my way!" "Show me your papers!" "Give me the money!"). Things that might count as charming banter in your culture ("May I help you cross the street?" "What glorious rainy weather!" "By the way, I come from Burundi") will be regarded in Germany as superficial blather and a waste of time.
Turning down invitations
If a German actually manages to invite you to his home to show you his own personal recycling system, you must never turn down the invitation. Otherwise, you'll make another enemy, and what it means to make enemies of Germans you can learn from any history book.
Speaking during meals
It is considered improper to speak during meals in Germany. According to old German custom, you should poke around the plate gloomily for a while, then suddenly choke it all down in one fell swoop. As soon as you see the German national dish, "Sludge with Goo and Meat," before you, you'll know why.
Conceal your fears
In Germany, culture, economy and cuisine are traditionally based on fear. Germans are accordingly proud of their fears and delight in spreading them. Currently, Germans are afraid about their pensions, dying-out as a nation, and being eliminated in the first round. Don't be afraid to talk about your own fears (floods, nuclear war, sauerkraut) -- but always admit that your hosts' fears are more important.
An inappropriate appearance can injure religious feelings in Germany. Of course, nobody will complain if Catholic Brazilian girls visit churches in their traditional costume of sequined bikinis. However if you happen to be in East Germany, you should avoid provoking the natives by having an unusual skin color. The ancient Germanic gods that are worshiped in these areas strictly forbid it.
Remaining sober during the evening
During the day, Germans like to appear lifeless and stony. During the evening, however, they drink several liters of beer and then suddenly go out of their minds and begin screaming like banshees. You should absolutely join in! Anyone who doesn't will quickly get smacked in the chops. Of course if you join in, you'll also get smacked in the chops, but you won't notice it as much.
Forgetting to mention the war
Never forget to mention the war to Germans! Germans love to prove, in hours-long conversations, that they know a lot about the rather unfortunate parts of their history, and that they've learned important things from it. As a follow-up, they'll be happy to explain to you all the things that suck about your country, and which genocides you should feel responsible for.
I hope this helps apprehensive tourists. Welcome to Germany, and don't forget to root for Tongo if Germany gets eliminated!