I'm not really sure where the saying "fired" and "unfired" came from but it refers to pretty much all lizards that can change their colors. Unfired is generally a gecko's resting color and is as dull as they get. Fully fired is generally when they are more active and is as bright and vibrant as they get. They can be at any stage in between throughout the day and every now and then they will even fire up some parts of their body and not others, which looks very silly!
Crested geckos and gargoyle geckos background colors generally get darker when they fire up.