Gao da shang is short for the Chinese phrase meaning high-end, grand and high-class, originally 高端大气上档次. Online, the shortened three-character form spread as a catchy buzzword in the 2010s and quickly turned ironic, used both to praise real luxury and to tease anything trying too hard to look expensive. That double meaning explains its life as a meme sound, where a single quick utterance can caption a glow-up, a flex or a parody of wealth without needing any further explanation in the video.