1989年5月23日，來自湖南的三名年輕人魯德成、喻東岳和余志堅，將染料和含墨水的雞蛋汁潑向天安門城樓上的毛澤東畫像。在廣場上的學生誤以為公安便衣蓄意製造事端抹黑，於是把三人交給國家公安部。他們被控「反革命破壞罪」和「反革命宣傳煽動罪」，魯德成被判處16年監禁，喻東岳被判20年，余志堅被判無期徒刑。2006年魯德成獲加拿大政治難民身份，2009年余志堅和喻東岳獲美國政治庇護。

On 23rd May, 1989, three young men, Lu Decheng, Yu Dongyue and Yu Zhijian, defaced Mao’s portrait on Tiananmen Square by splattering paint and eggs on it. The portrait was quickly covered. Many students were infuriated with the defacement, claiming that the vandals must have been government agents hoping to discredit the students’ cause. The three men were immediately caught by the students and later turned in to the police. Lu Decheng was sentenced to 16 years, Yu Dongyue 20 years and Yu Zhijian life in prison. Later in 2006 and 2009, they became political refugees and were grounded asylum in North America.