Gorgie biscuit, n. — Green’s Dictionary of Slang

Gorgie biscuit n.

[Gorgie, a suburb to the west of Edinburgh; home 1888-1969 of McVitie's, manufacturer of the first ‘digestive biscuits’]

during a fight, to smash one’s forehead into one’s opponent’s face.

1984

(con. WWII) T. Jones Heart of Oak [ebook] I turned fast and got both fists into his face. While he staggered, I put the boot in [...] I was going to give him the Gorgie Biscuit when a gang of locals grabbed me and calmed me down.