“Qunar (去哪儿, Where to)?” Beijing cabbies typically ask when they pick up a fare. But the out-of-town rider who replies “Qianmenr” en route to catching an exhibition at the Dashilar hutongs is likely to earn blank eyes of scorn from these natives of the capital.

The “er” sound, represented by the character 儿, is as closely associated with Beijing’s dialect as politics is with its taxi drivers, and pingshu commentary with its radio shows. Although other northern Chinese dialects—such as that of the Northeast (Dongbei)—feature 儿 afterwords, Beijing’s rhotic patter has been made iconic by cultural exports like crosstalk.

Beijingers typically explain that adding 儿 to words, a process known as erhua (儿化), serves to indicate the size, the cuteness, or one’s fondness of the object, or just to better the flow of conversation. The rules of what can and cannot be erhua, though, are notoriously inconsistent: Why, for instance, can a restaurant be called fanguanr (饭馆儿), while a museum must be bowuguan (博物馆)?

According to Shi Yi, a Beijing native and Chinese instructor at Peking University, the rules for erhua are mostly intuitive. Still, she attempts to categorize three broad functions of 儿 to help non-natives understand where it can be used—or at least, avoid embarrassing themselves in situations where it can’t:

1. Casualness

Shi says that 儿 rolls off of the tongue and is easy to combine with phrases. “Beijing dialect is kind of lazy, I think. Like 今天儿不错 (it’s a beautiful day)  is very comfortable [to say] when you say 儿 with 天.” 

However, she says that 儿 is meant for casual situations only, as it gives word the character of slang. “The character of Beijingers is outgoing and talkative. Some local Beijingers, especially elderly people who live in hutongs, are carefree and satisfied with their life,” Shi says. “I think it is the same feeling when you pronounce 儿 , your tongue is very relaxed and bent a little, just like you’re stretching yourself.” 

2. Size

Since 儿 indicates casualness, adding it to a word reduces its size or significance. Restaurants and cafes (咖啡馆), lively locales where people socialize, eat, and relax, can be erhua, but more grand or businesslike locations such as museums or swimming complexes (游泳馆) cannot.

Similarly, while it’s acceptable to refer to generic doors as mer (门 儿), locations named after gates on Beijing’s old inner-city walls must remain 儿-less due to their historical prestige: Dongzhimen (东直门), Qianmen (前门), Xizhimen (西直门), and so forth. The only gate names on which it’s acceptable to add 儿 are Dongbianmenr (东便门儿) and Xibianmenr (西便门儿), two less-important gates on the outer wall. This gives rise to the old joke where a Beijing bus conductor shouts, “前门到了，请从后门儿下车 (We are arriving at Qianmen [front gate of the old city wall], please get off at the back door).”

儿 is also added to the end of people’s names to indicate fondness. “儿 is just tiny, cute, and it makes you feel very close to people,” says Shi. 

3. Semantics

While adding 儿 to words like 天 doesn’t change the meaning, and is purely an aesthetic choice, erhua does have a semantic function sometimes. For example, gai (盖) is the verb “to cover,” but gar (盖儿) is usually understood to mean “lid,” a noun.

Zhou Yi, a professor of Chinese language at Peking University originally from southern China, says that most uses of 儿 are just personal preference. Not even native Beijingers may use them consistently or in every conversation. “Some people use it, some people don’t,” Zhou says. “As I have lived in Beijing for more than 10 years, I am getting used to using 儿 in my daily life.”

Wang Yu, a PhD student at Peking University, has lived in the city since he was 8 years old, and always spoke with erhua in primary school and high school. However, since going to university, he has tried to curb his dialect. “At Peking University, all the people are from other cities, [and] a lot of people [are] from the south of China, so I speak Putonghua.”

Among his fellow Beijing natives, though, 儿 sounds roll of Wang’s tongue, and he revels in the sense of community this gives him. “I think it [makes Beijingers feel] very familiar to speak Beijinghua. [Like] we are one people, from Beijing, and intimately connected with each other.”