breeee

Is a sound produced by forcingn air backwards down your throat, vibrating your vocal chords the opposite direction to normal speech, making a "bree" or pig squeal sound, movement of the mouth and jaw can alter the sound produced, as can the starting "Letter" you used to make the sound e.g Gree.
This sound can be produced through exhaling alse making a gurgling phelgmy sound but at a quieter noise level