It's a loan word from Japanese.
Often pronounced so as to rhyme with the way a person with a New York City accent would say "poker." Not quite the way it is pronounced in Japan but close enough. Besides, this is America. We should speak 'Merikan, not Jap'neez.
I prefer to say "blur." That's supposed to be what "bokeh" means in Japanese... But it also means "senile" or "crazy."