Green’s Dictionary of Slang

core v.

[Rom. cor, to steal]

to steal small articles from shops (cf. chore v.).

[Scot]D. Haggart Autobiog. 38: We were principally engaged upon the hoys and coreing.
[Scot]I. Welsh Trainspotting 121: The adrenalin kick makes us want tae head up the toon, oan a choryin spree, like.