You hear it a lot in Polish, even though/because it ignores normal grammatical rules (ie it doesn't agree with nouns). But did it really become trendy in English from German?
Not in a position to say. I first heard it in German 30 years ago from the mouth of a Herr Doktor N. as he had his first suck of margarita in Colorado: Oh, das ist s
oooper!
It's funny. You expect your own language to evolve with time, but when you've gone to the trouble of learning a different one you rather expect the foreigns not to go changing things behind your back.
Incidentally, in the 70s I learnt that it was very ill-bred to say "hallo"; now it seems to be the standard casual greeting, at least in the Rheinpfalz.