I recall one phone call where the guy said "how much do you know about Ajax?" (pronounced like the Dutch football team). There was no reason for the guy to know any different, but it amused me at the time....
Someone like me probably set them down the wrong path!
You'd probably be hard pressed to understand what they're talking about :) - for example JSON is definitely JASON, and you'll be looked at funny if you don't pronounce it that way :) , and Ajax is pronounced like the Dutch football team.
If I don't hear it on a video or a talk, I'm probably pronouncing it wrong (and not knowing I am). I hope to get corrected if I do.
I worked on a portlet system a few years back (oh the horror!) with a Chinese dude. Super developer. It wasn't until the last day that I figured out what he meant when he said 'poorer led'. Should have figured it out sooner looking back :D