This has nothing to do with carbonated drinks, goblin-like creatures or the Texas Instruments TMS9918.
A CSS sprite is an single image file that contains two or more actual images (e.g. the top half is a button image, the bottom half is an on-click button-down image) which are shown individually by using CSS. This cuts down on http requests and therefore cuts down on loading times.
Soh Tanaka has a good example which uses CSS sprites to make a greyscale-on-mouse-over image.