Americans typically arrive in Germany, and suddenly find this magical and mythical kingdom.... where consumption of alcohol reaches a level that we never dreamed of. After a while....you have to have some understandings and rules about booze in Germany.
First, it's true....at age sixteen....you can consume beer and wine (no booze). Don't ask the logic to this. At age sixteen.....you can buy the beer and wine without standing around adults. At age eighteen, you can consume anything your heart desires. Now, all this said....are there issues? Twenty years ago? No. Today, a majority of Germans think that the punks are abusing booze and there's a national problem with teenage drinking. And yes, an American teenager visiting in Germany or a military-dependent kid.....gets the same privilege You can imagine a 16-year old American kid arriving and finding this out.
Second, if you look kinda young....every single grocery will ID you at the counter. Bars and pubs? It might be a different story, and the majority will just smile as you order your brew and never ask for an ID.
Third, the authorities in Germany will rarely if ever....ban alcohol. Now, that said....you might encounter a soccer match where the local cops have dictated all beer sales stop at the half-time point. This is mostly done to prevent drunken brawls after the game. If the beer tap stays open till the end of the game...it's usually the best time as an American to just stand back and watch drunk Germans battle each other over soccer scores.
Fourth, if the German cops pull you over and you fail the DWI exam....you are screwed. Your insurance goes up....your license goes away for months....and the next six to twelve months will be absolutely miserable. So if you want to drink excessively....drink around your house or apartment block....and walk home. Don't take any risks because the cops don't have compassion about this stuff.
Fifth, beer can be served in 1-liter steins. If you've never encountered a 1-liter stein....you might want to view it before ordering it. A 160-pound adult can be reasonable drunk from just one stein in an hour. If you move onto two steins in two hours....you are consuming a fair amount of beer. My general advice is to stay at the half-liter stein level.
Sixth, wine consumption in Germany is a big deal, and you could sit and enjoy six to eight glasses of wine over an entire evening. It's best not to consider driving, in a state like this.
Seventh, it actually gets hot in July and August in Germany. You might stop at a outdoor situation, sipping down a ice-cold beer, and then go for a second in a hydration attempt. My advice....order yourself a bottle of water to start, and then shift to the beer. Beer is a poor choice for hydrating yourself.
Eighth, Germans tend to have a pretty low opinion of folks who drink excessively and throw up. If you do something this stupid....try to immediately start speaking British phrases and acting English....make them think you are British (not American). I admit, it builds up more anti-British sentiment, but it's not like they can ever deduct any negativity from the British image in Germany anyway.
Ninth, if you are in some downtown Frankfurt or Hamburg bar with buy-me-a-drink women around....be aware that they can choose a 60-Euro bottle of fancy bubble-wine, and your bar-tab could suddenly run up to two hundred Euro in just an hour. Skip these bars.
Tenth, do not ever make the mistake of discussing American-brewed beer with a German, and trying to say that some American beers come close to the German taste. They will feel insulted, and this brings on an hour-long argument about you being dead-wrong on this issue. Course, you could sneak in a Pabst-Blue-Ribbon on the German during the argument, and they'd likely never notice. Just be forewarned about this potential for an argument.