Joke explainer: "Yi," "Er," and "San" are (the partial transcriptions in the Latin alphabet of the most common words for) "One", "Two," and "Three" in Chinese.

Joke explainer: "Yi," "Er," and "San" are (the partial transcriptions in the Latin alphabet of the most common words for) "One", "Two," and "Three" in Chinese. I’m assuming that 'Yi' was used because it unifies several ideas. I’m also happy it’s an easy naming convention that is not an animal.