Gaoli bangzi (Chinese: 高麗棒子; pinyin: gāolì bàngzi) is a common Chinese slang term, and has a long history of being used as a deprecatory ethnic slur for Koreans. The term gaoli (高麗) refers to the ancient Korean dynasty Goryeo, while bangzi (棒子) means billy club. It is used synonymously with Er Guizi (二鬼子) and is sometimes shortened to han bangzi (韓棒子) or simply bangzi (棒子).
One popular but incorrect belief is that the term originated from the baton-wielding Korean guards during the Japanese occupation of Manchuria. According to this account, the Japanese distrusted the Korean guards and did not issue them firearms, only allowing them to equip themselves with the Bangmangi washing bats commonly found in Korean households. The guards often enjoyed teasing Chinese people and beating them with batons, earning enmity among the Chinese populace. However, the use of this slang term has been seen as early as the reign of the Kangxi Emperor two centuries before, so this explanation does not stand up to scrutiny. At present the exact origin of "Gaoli Bangzi" remains uncertain.
The term's earliest mention in writing is in the 1722-published Chinese journal Liaozuo Jianwenlu (Chinese: 遼左見聞錄) by Chinese traveller Wang Yiyuan, which recorded that the lower class in Korea, specifically citing the children of prostitutes, were referred to as "Bangzi".
Huang Puji of the Nanjing University Department of History argues that the term originated as the Chinese language near-homophone "帮子" which means "helper", referring to the servants and labourers who accompanied Korean diplomatic missions to China in large numbers during the Ming and Qing Dynasties, but this mistakenly became corrupted as "棒子", a term which differs only in tone. These poverty-stricken servants had apparently gained a reputation for petty crimes such as smuggling, according to the diary of Korean scholar Kim Chang-eop (Hanja: 金昌業). and subsequently its usage expanded to refer to all Koreans in Chinese public perception.
The term "helper" (帮子) was also used this way to refer to the embassy's servantry by Hong Dae-yong (Hangul: 홍대용; hanja: 洪大容) in the diary of his visit to China Eul-byeong Yeon-haeng-log (Hangul: 을병연행록; hanja: 乙丙燕行錄).
In the First Volume of the Qianglong period court document Huangqing Zhigongtu (Chinese: 皇清職貢圖, literally "Portraits of Periodical Offering of the Qing"), the entry regarding Koreans includes the statement: "朝鮮國民人，俗呼為高麗棒子。" (Joseon citizens, colloquially referred to as Goryeo bangzi) 
- "郭台銘：與夏普合作有信心打敗三星". Chosun Ilbo. 2012-06-20. Retrieved 2012-09-30.
- "THE WORLD; China and North Korea: Not-So-Best of Friends". New York Times. 1993-04-11. Retrieved 2012-09-30.
- ""高丽棒子"一词的由来". 新华网. 南京大学学报. 2013-06-09. Retrieved 2013-11-28.
- The dictionary definition of gaoli bangzi at Wiktionary