黄 (huáng): Yellow. The color yellow is culturally significant in China, often associated with the emperor and the Yellow River. However, its meaning here is historical and less direct.
牛 (niú): Ox / Cow / Bull. A symbol of strength, diligence, and sometimes stubbornness.
党 (dǎng): Party / Group / Gang. This character is crucial as it implies an organized, collective entity rather than just an individual. It's the same character used in 共产党 (Gòngchǎndǎng), the Communist Party.
The combination “yellow ox” (黄牛) is said to have originated in Shanghai in the early 20th century. The chaotic crowds queuing for tickets were likened to a herd of cattle (牛). The scalpers, who would weave through the crowds making deals, were given this nickname. The addition of “党” (group/gang) came later, reflecting their increasingly organized and large-scale operations.