I've always pronounced it "jref," like one weird syllable. No, no, I'm just kidding, actually. But "jref" sounds like it'd make a good slang term, doesn't it? ("Man, you're lookin' pretty jref today!" "Thanks, man!")
Anywho, I've always pronounced it "jay-ref." It mildly surprises me that there are native English speakers that don't do so, as it seems the most natural. Not that there's anything wrong with that. I'm just sayin'.
I thought I posted this earlier today.