I can't, I don't understand
From China Digital Space
bù néng, bù míngbai | 不能，不明白
In late December 2019, Dr. Li posted to a closed WeChat group about a "SARS-like" illness originating in a wet market in Wuhan. On January 3, two officers from the local Public Security Bureau forced Dr. Li to fingerprint a notice as agreement to cease from "publishing untrue discourse on the internet":
...The public security bureau hopes that you will actively cooperate with our work, follow the advice of the police, and stop the illegal behavior. Can you do this?
We hope that you can calm down and earnestly reflect, and solemnly warn you: If you are stubborn, refuse to repent, and continue to carry out illegal activities, you will be punished by the law! Do you understand?
Answer: Understood [Source]
Dr. Li died of COVID-19 on February 7, sending waves of grief and anger through the Chinese-speaking world that were amplified by the state's initial reports that he was still undergoing treatment. A leaked photo of Dr. Li's "admonishment notice" triggered an online campaign to take a selfie with a sign, often written on a face mask, defiantly answering the same questions Public Security posed to Dr. Li. A montage of photos made its way onto the video-sharing platform TikTok. The campaign gathered enough momentum for the censors to strike back: Weibo users who tried to post the text "I can't, I don't understand" received warnings that their words were "in violation of the relevant laws and regulations" and were invisible to other users.
@k***_: I can't, I don't understand. I know that everything will disappear, I know that everyone will be forgotten, but I will remember that I can't [Chinese]
See also we want free speech.