Saying from York, UK meaning that a certain form of behaviour is unacceptable - implication that it wouldn't be acceptable in the village of Snaith, near York. The behaviour is so unacceptable that, to personify it, never mind walking or running, it would be unable to even slither around Snaith before being challenged.
"That gentleman has just disobeyed traffic laws and displayed a rude gesture, informing me that I am a masturbator. That wouldn't slither down in Snaith!"
Used to describe the most unimaginably appalling and utterly disgraceful person. This word should be used in moderation, as hearing it makes you want to snort your filthy phlegm into the back of your throat and spit it out onto whatever putrid being said such word.
Friend 1: Did you hear about what Zac did to Marco the other night?
Friend 2: Yeah, what an absolute snith.