An employee of a fast-food restaurant in Beijing literally did the same thing. We had just arrived on our very first trip to Asia and walked across the street from our large tourist hotel to this establishment. She was very kind, helpful and friendly as we pointed at the items we wanted, and we left some small amount on the table with the total as a thank-you.

She literally ran out the door after us and pressed the money into our hands, almost as if she would have been in trouble for accepting it.

We felt bad that our tip had the reverse effect of what we'd intended but we parted with smiles and our mangled version of xie xie.