An expletive usually expressing disbelief or exasperation. It is the opposite to that of a Christian person saying ‘Christ on the cross.’ Somewhat akin to saying ‘Shit on a stick.’
A more "embellished" phrase of the classic saying "Holy shit"!
An example of when to use it would be after excessive amounts of exertion to illustrate the mixture of exhaustion and lack of giving a crap about whats coming out of your mouth.