Judging from the screenshot, I agree with Kllrwlf, i.e. it's probably just some guy thinking you are Chinese. Basically the conversation went:

Him: Where you from? I don't know how to say it.
You: I'm sorry.
You: I'm American.
Him: So funny/Laughing my ass off.
Him: I'm British.
You: I'm sorry I don't understand. Goodbye.

Btw Mandarin is the spoken language. Traditional Chinese is the written script, the other form being Simplified Chinese.

I like the names of your toons btw.