Sir_Didier_Drogba mostly hit the nail on the head - though remember his is a bit of a hipster.
Oh and kebab - Jabo is right. In fact I've heard that Berlin is the home if what western society calls the kebab. They were invented there, not the middle east, based on something similar in the middle east (or something like that).
Berlin isn't quite the home of Pork and beer - that's more Bavaria (Munich), or further east in Europe, bit they still do a good job.
They LOVE their clubs and house sort of music there too.
Currywurst is good too, as Sir_Didier_Drogba said (though mine always came with curry powder, and a curry flavoured sauce - which may have been tomato based), definitely try it at least once if you don't mind eating pork. It's not the world best good, but little pieces of meat, for not much money are a great street snack.
There are also some really good chocolate shops in Berlin now - where you can make your own custom box and stuff, which is great if you're into that sort of stuff (or bringing your gf).
I actually did a ridiculously good Third Reich walking tour (which also went over some cold war history). The chick that guided us was a German uni student, who spoke perfect English. It was very very interesting.
It really is a great night life city though. Head out, and don't stay at one bar too long. So many cool bars to see