It's just an expletive that expresses light disapproval about something that someone's saying.
Mr X: "I'm going to the club Fabric tomorrow night"
Mrs Y: "Bleurgh! It's such a rip off and Embassy is way better!".
OR:
Mr X: "Sorry but I really can't talk now, I've got way too much to do."
Mrs Y: "Bleurgh! You never make time for me anymore".
It's just a light-hearted expression for disapproval :).
Take care!