Why do most jews have German last names?

Most Jews don't. Remember, there are Indian Jews, Japanese Jews, Swedish Jews, Yemenite Jews, British Jews, Ethiopian Jews...

You're thinking of Ashkenasi Jews; Jews who ended up in Europe. Many of them lived in Germany and so yes, their names would have been Germanic, just as Russian Jews' names would have reflected the Russian heritage.

50% of Israelis are native to the Middle East or North Africa - so they too won't have European names.

You also need to remember that MANY Jews' surnames were changed by the immigration officials in America and Britain and other nations. The officials often couldn't understand what the actual surnames were, so they would write down the nearest approximation they could manage.

German was the lingua franca of Eastern Europe where Ashkenazi Jews lived but there are other ethnicities of Jews Such as Sephardi Jews of Spain (they were the majority of Jews a few hundred years ago)

yeah, it's probably because most of the jews living in the usa are descendants of the fugitives from germany. but what I'm wondering is, why did they change their jewish names to german in the first place. I mean, original,jewish names aren't such tounge-breakers. if they changed their names in order to integrate into the german society, why did most of them use this same 2 word-pattern (zucker+berg, gold+blum, spiel+berg), which make them so recognizable?

Because some are German Jews?

I don't. MOST jews don't either. Many Jewish people ran over to the U.S. from Germany during WWII, so you may just be seeing the descendants of the persecuted.

Maybe many of them are from Germany. Judaism is only a religion, they don't neccessarily have to only be from Israel...

My boss is Jewish, his last name is Dorra and he is from Egypt.