Bluh-kyaq!
Onomatopoeic interjection used to describe something unexpected (particularly of unusual size or swiftness) appearing in close proximity, particularly to one's face
Man, I turned around and your sunglasses were like "Bluh-kyack!" all up in ma face.
Person 1: Man! I can't believe you just slapped me like that!
Person 2: Bluh-kyack!
Person 1: Man! I can't believe you just slapped me like that!
Person 2: Bluh-kyack!