Heard in Mid-Cheshire, England, a lot when I was a kid there. A rural term, so maybe this should be in a 'RuralDictionary' section! 'yoskers' is an insulting term akin to 'peasants' - for example, it refers to farm-workers, or the families that only seem to rear farm-workers.
Q. Where does Bob Turbishley work now? - haven't seen him since school . .
A. Bob? Works down at Ashley's farm - always was a yosker, like all the rest of the Turbishleys . .