Mei you is a common Mandarin phrase meaning there is none, there is not, or do not have, and short voice clips of it circulate online as a quick reaction sound. Because the phrase is short, direct, and easy to recognise even for listeners who do not speak Mandarin, creators use it as a punchline for absence, refusal, and disappointment. Its under-a-second length makes it easy to drop into fast edits, subtitles, and reaction videos, where a longer explanation would slow the joke down.