“Rate of Penetration of a Porcupine Spine,” Albert R. Shadle and Donald Po-Chedley, Journal of Mammalogy, vol. 30, no. 2, May 1949, pp. 172–3 (http://dx.doi.org/10.2307/1375267).
The authors report that:
During the examination of one of the porcupines in the vivarium of the University of Buffalo, the animal became excited, and, as a result of its struggle, fell backwards from the porcelain top of the table. She fell upon the antero-lateral surface of the junior author’s right leg, embedding her spines primarily in the belly of the tibialis anterior muscle.
(That’s an except from the article “Improbable Research Review,” Published in AIR 13:4.)