the meaning is slightly changed... a shit bastard
is a person who is annoying for some reason, the phrase "shitbas" is used for describing something or an explanation of annoyance or displeasure.
Tom: "Man, i lost
the car keys, way out there in the jungle"
Tim: "Argh Tom, you shit
bastard, how could
you do that?!"
"Crap, my CD is broken!"
"Na, don't matter, it was shitbas anyway..."
hit my faffing
head on the door!"