A combination of the words "shit" and "sabbatical." When you have to take a crap and you know it will take a while and you requires some form of entertainment while doing your business. When going "on shibbatical" one might take a laptop, telephone, book, homework assignment, magazine, gameboy, or perhaps a portable television.
"Hey John O, where are you going with your laptop?"
"Dude, I ate a shitload of taco bell earlier, I'm going on shibbatical."
Amazing piece of work that is created between the inner sanctums of your brain. This is referred to as something someone may have said thought or done. It is an adjective to describe any all and what. USE IT!