Barggle is an expression of emotion. It is used when mumbling incoherent grumbles of sounds to express the whatever irritation and complaint that your heart is feeling. Or it may be used when you are a combination of annoyed and sad. It signifies the very end of all of your emotional complaint.
Steph: Did you eat all of my chocolate cheesecake?
Andy: Yes, it was very delicious
Steph: BAHR!! I get no respeck 'round here! *whimpers* Barggle.