This piece in Taki’s Magazine is a list of some of the more colorful prison slang that Dalrymple experienced. I always find his writings on this topic tremendously funny, and in person he delivers these expressions and phrases fully in character with funny accents and a big smile.
…when I started working in prison I was sometimes called to attend a prisoner who had just been PP9’d. A PP9 was a large, squarish battery that was used (in respectable circles) to power transistor radios; but in prison it was sometimes put in a sock and swung round like the bola of an Argentinean gaucho, inflicting quite serious injury on the head of the person at whom it was aimed. Such batteries soon became technologically redundant, however, and the verb went out with them. No one is PP9’d these days. I suppose that is progress.