The phrase is written using Zhuyin, also called Bopomofo, the phonetic system commonly used in Taiwan, mixed with regular Chinese characters for you and la. Writing an insult this way is a common online workaround, letting users post or search for a well known profane expression without spelling it in full characters. Clips of the shouted version circulate on user generated soundboards as a compact reaction audio, shared in chats and short edits where a one second burst of swearing says more than a longer rant or explanation ever could in memes.