Vegging out vs. geeking out

Modern English has given us two terms we need to explain this phenomenon: "geeking out" and "vegging out." To geek out on something means to immerse yourself in its details to an extent that is distinctly abnormal - and to have a good time doing it. To veg out, by contrast, means to enter a passive state and allow sounds and images to wash over you without troubling yourself too much about what it all means.

From Neal Stephenson's NY Times piece.