wo dao He Bei sheng lai

In the german movie "Der Untergang", Hitler (actor Bruno Ganz) said "und doch habe ich allein...", which sounds almost exactly same as "I go to Hebei province (a real province in China)" in Chinese

wo dao he bei sheng lai,俺来不是闲得蛋疼，天朝好棒好棒的

db

DB is the shorten form of "Deutsche Bahn", the German Railways, which is well-known for being late.

DB:"Zug fährt nicht, laufen" (the train is cancelled, run)

i

Square root of (-1)

(a+bi)(c+di)=ac-bd+(ad+bc)i