When I type :cup: I get the image correctly -
The short code/long code doesn't have anything to do with it. The point is if you're already using :n then :no: will get confused, it'll conver the :n to the image and you'll just have o: displayed.
<img src="https://www.ubbcentral.com/boards/images/graemlins/tongue.gif" alt="" /> Still not following what your question or problem is. <img src="https://www.ubbcentral.com/boards/images/graemlins/tongue.gif" alt="" />