你蒙你梦你猛
[nĭ mĕng nĭ mèng nĭ mĕng]
A rather colloquial and playful phrase used to scold someone mildly or jokingly. The first two words '你蒙' and '你梦' both could mean you guess, while '你猛' means you're fierce/aggressive. The meaning is something along the lines of 'You bluff, you daydream, how dare you!'