SO Losian is gross and makes this amazing/awful noise with his lips and I was inspired. I designed the monster that makes this noise.
The Floggiloat is a creature whose communication is done exclusively through the wet slapping noises made from exhaling against the fleshy wattles surrounding its face. It does this as part of its mating courtship, when startled, in greeting, etc. It possesses no vocal chords, but the flapping can be heard up to a half a mile away by others of its species.
The sound can be heard by clicking here.