Jackie protests: the correct sound is the same a-sound as in flack, not flock! Though there are some US'ns who use that sound, notably Will Smith in Men In Black, when he said, "Oh, was that your Ontie?"

I think this is regional. There are even those who go so far as to pronounce it AWNT, notably Garrison Keillor from A Prairie Home Companion (unspeakable perversion).