This timeless piece of “body art” of people having sex in an MRI turns 20

Christmas just wouldn't be the same for lovers of science without the annual Christmas issue of the British Medical Journal (BMJ). The tradition began in 1982, originally as a one-off attempt to bring a bit of levity to the journal for the holidays. While the papers selected for inclusion evinced a quirky sense of humor, they were also peer-reviewed and scientifically rigorous.

Some of the more notable offerings over the last 37 years included the side effects of sword-swallowing; a thermal imaging study on reindeer offering a possible explanation for why Rudolph's nose was so red; and an analysis of the superior antioxidant properties of martinis that are shaken, not stirred. (Conclusion: "007's profound state of health may be due, at least in part, to compliant bartenders.")

But by far the most widely read Christmas issue paper was a 1999 study that produced the very first MRI images of a human couple having sex. In so doing, the researchers busted a couple of long-standing myths about the anatomical peculiarities of the male and female sexual organs during sex. Naturally, the study was a shoo-in for the 2000 Ig Nobel Prize for Medicine.