Green’s Dictionary of Slang

pumpkin head v.

(US prison) to beat up a victim using a pillowcase containing some form of hard object.

[US]Other Side of the Wall: Prisoner’s Dict. July 🌐 Pumpkin Head: To have put something in pillow case and beaten somebody with it until their face becomes bruised or a ‘pumpkin head.’ Also, to give a ‘pumpkin head degree.’.