This paper reports on my first-hand experiences of being a "purist" in Hong Kong, during which time I was not allowed to use mixed code, a common discursive practice among Hongkongers in Hong Kong. I shall discuss the difficulties in using "pure" English and "pure" Chinese in my daily life, as well as exploring the problems I encountered when I used "pure" English in teaching English to a small group of ESL students at a primary school in Hong Kong. I argue that mixed code is very much characteristic of everyday language use by most Hongkongers and represents an important marker of their ethno-linguistic identity. In relation to language teaching, I suggest that mixed code may be usefully adopted in teaching English in Hong Kong, rather than being shunned at all costs.