Another tale of the Stealth Sinoglot

I head to the kitchen in our building to get a cup of coffee. The coffee machine is brewing one already, so I wait.

There are two Chinese women there as well, washing their lunch containers and gossiping about people on the team in Chinese. "He's such a jerk... she's worse... he smells..." and so on.

Eventually the machine finishes, but neither of the women make a move towards the coffee. After a bit they glance at me, and then at the coffee, and then at each other.

"Whose coffee is that?"

"No idea."

They glance at me.

"Oh, it's neither of yours? I'll just move it, then. Thanks."

They studiously ignore me while they finish packing their stuff up in silence.