An adjective. It refers to a particular thing being of the the form, a 'crapsack'. a crapsack is a sack filled with crap. Cracpsackular is used to define the awesomeness of something. Crapsackular, means that that something is really quite shit.
Wow, i just went and saw the movie "confessions of a shopaholic" and let me tell u... It was mighty crapsackular!