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."