Adding Spice to the Porridge11'Porridge' Is British Slang for a Prison Sentence. E.g. 'Doing His Porridge'. The Term Is Most Commonly Thought to Be an Allusion to the Fact That Porridge Is, or Used to Be, a Common Food in Prison. The Term Is Also Thought to Be a Pun on the Much Older Slang Word for Prison, 'Stir'.: The Development of a Synthetic Cannabinoid Market in an English Prison