In Chinese, "没有”, pronounced "may yo", means "Without," or "It isn't," or any such thing. It essentially means "I don't have it" or "It doesn't exist."
If you go to a Subway in Xi'an, most of the employees will speak at least a sandwich-aware version of English, wherein you can list ingredients and they'll know what's going on. When they get to the sauces, and they ask if you want any, and you say "Mayo", there's almost always a moment of hesitation when they try and decide if you mean "Mayo" or "没有”.
It's the little things in life that keep you smiling.