An expression of surprise or shock that is an extension of the phrase 'Shit fire' Used primarily by people in the southern and mid western U.S.
"She's going to what? Well if she shaves her head, I'll shit fire and save the matches."
"Shit fire and save the matches! There's no way you really won at the casino."
A paniced state of confusion where there are multiple obvious choices for courses of action, but the subject, overwhelmed and shocked, freezes up and does nothing.
Bill was flirting with this gorgeousbabe all night then when she took her top off, he didn't know wether to shit or wind his watch!!!