The NVSH used to have an advertisement with the slogan in big capitals: "How do two hedgehogs do it?" and the answer in a much smaller type:"Very careful". Porcupines are even more prickly, but they go at it like animals. Frottage, golden showers, extreme violence, you name it, they practice it.
How do we know? A correspondent of the Annals of Improbable Research found two papers in the basement of the Australian National University, describing in great detail the details of the porcupine’s sex life. The contents of the paper was so important that she wrote an article about it.
Next time a friend asks about the porcupine's sex life, you can describe it as vivid as you dare.