'Āi yō wèi' is a highly expressive, exaggerated interjection used to convey sudden, humorous dismay—like stubbing your toe, dropping your phone, or hearing shocking news. Though it looks like three separate characters, it functions as a single unit with no literal meaning; each syllable contributes to its theatrical, drawn-out sound. It's not a compound word but an emphatic vocalization, often delivered with a rising-falling tone and widened eyes for comic effect.

This phrase belongs to informal spoken Chinese and appears frequently in sitcoms, online videos, and daily banter among friends or family. It’s more playful and less serious than simpler exclamations like 'āi yō' or 'tiān a', and the extra 'wèi' adds a layer of mock despair or theatrical flair. Native speakers rarely use it in writing unless mimicking speech, and it’s almost never appropriate in formal or professional contexts.