What does this dream mean?

Its about temptation and your motivations for doing things. You obviously didn't need the coffee and it wasn't really yours anyway but because it was free you drank it out of a feeling of obligation. Then you felt guilty for it because what you are really doing is not respecting your own boundaries. I'm not sure your exact reasons for going to the buffet, maybe lust or again obligation or guilt or just going along with what is accepted but the end result is that you feel bad about yourself because you are not respecting yourself and your own integrity. This is God trying to warn you that you need to develop your integrity and stand up for yourself. (I know because I've had the same type of dream so there's no judgment from me.) If you continue to do this to yourself you will end up in worse and worse situations until you are quite miserable and you don't even know who you are anymore. I suggest reading this book on healthy boundaries a href="http://www.amazon.com/Boundaries-When-Take-Control-Your/dp/0310247454" rel="nofollow"http://www.amazon.com/Boundaries-When-Ta…/a or something similar.