A shit witch is a girl that is cute, rich, and popular but behaves in the most ugly of manners. Shit witches are tasked by the Devil with making the world a much worse place.
Wendy is a shit witch, dude. It's just the way it is.
The number by which something is multiplied when prefaced with "shit". This is typically somewhere between 1.5x - 2x. However, many interpretations have placed the shit multiplier as high as 20x.
"Whoa, that is a shit ton of shit." "What shitmultiplier are you applying to that shit?"