A North-Eastern (England) term for pretty much everything. It can be used to greet, to grab attention, or to show disgust, these being only a few of its meanings.
Rather than pronounced 'Oooo' its literally pronounced 'ew', elongated, it would sound like a post 'Oh'.
Ew mate, how you doing?
Ew, I totally bucked this lass last night.
Ew no you can't say that man!