2012 Kong Qingdong incident

In January 2012, Peking University professor Kong Qingdong made televised remarks suggesting that many Hongkongers were disloyal to China and still harboured a colonial mentality. Kong Qingdong said many Hongkongers were "dogs" in response to an online video posted about a mainland Chinese child eating on the subway, which is prohibited by MTR regulations, and being harassed despite having stopped eating subsequently.

Source: Wikipedia — 2012 Kong Qingdong incident (CC BY-SA 4.0)