'Shit-boy' is a term to acknowledge surprise or shock to any situation. It can be used in an extensive range of circumstances, from mocking a friend that has done something trivial, to a response upon hearing the gravest of news.
The tone of delivery,
facial expressions and relationship are essential to the perception of
sincerity/ use of the term.
A group of friends arrive at the airport to go on holiday.
"I forgot my
passport"
Inhale and sympathetic.."..
shit boy".
An outstandingly attractive group of girls walk past in the street.
A glance to your friend and a
cheeky smile.."Shit-boy".