Chinese at the Chiang Mai Night Bazaar

I went to the Chiang Mai Night Bazaar. It's fairly well known around Thailand and you are supposed to be able to get better deals there than elsewhere. I was bargaining for a pair of linen pants and discussing the price with my white friend in Chinese so I could give the saleswoman a counter offer when she said "san bai!" I was like, uh oh, she's heard and understood the whole time, but it turned out she only knew her numbers in Chinese. Then a few stops later, I was trying to buy a scarf and we were speaking to each other in Chinese again, and the vendor switches the entire conversation into Chinese. So there we are in the middle of Thailand, three non-native Chinese speakers, speaking Chinese to each other, haggling over the price of a scarf.