You're looking at a figure from a groundbreaking scientific paper published in European Urology by Dr. Ahmed Shafik of the Cairo University in Egypt. In the 1993 paper, Dr. Shafik explored the effect of wearing different types of underpants on the sexual activities of rats. He dressed 75 rats in a) 100% polyester, b) 50/50 polyester/cotton, c) 100% cotton and d) 100% wool underpants for one year.
What did Dr. Shafik find? Rats that wore 100% polyester pants had significantly less sex than those wearing underwear made from other fabric (he blamed it on the "electrostatic field" effect of polyester!)
What? Don't believe me? Here's the abstract from European Urology 1993; 24: 375-380:
The effect of wearing different types of textiles on sexual activity was studied in 75 rats which were divided into five equal groups: four test groups and one control. Each of the four test groups were dressed in one type of textile pants made of either 100% polyester, 50/50% polyester/cotton mix, 100% cotton or 100% wool. Sexual behavior was assessed before and after 6 and 12 months of wearing the pants and 6 months after their removal. The rate of intromission to mounting (IIM) was determined. The electrostatic potentials generated on penis and scrotum were also measured by electrostatic kilovoltmeter. At 6 and 12 months of wearing the polyester and polyester-cotton mix pants, the I/M ratio was significantly reduced compared to the pre-test levels and the controls (p < 0.0001). The reduction was more manifest in the polyester than in the polyester-cotton mix group, and at the 12th month than at the 6th month of examination. The I/M ratio of the cotton and wool groups showed insignificant changes (p > 0.05) at the 6th month of the study and a significant increase at the 12th month (p < 0.01). Six months after removal of the pants, the I/M ratio returned to the pre-test levels (p > 0.05) in the four groups. The polyester-containing pants generated electrostatic potentials while the other textiles did not. These potentials seem to induce "electrostatic fields" in the intrapenile structures, which could explain the decrease in the rats' sexual activity.
The figure above, titled "The underpant worn by the rat," is made famous by Mary Roach's new book about the science of sex called "Bonk: The Curious Coupling of Science and Sex." NPR has a really neat excerpt about the paper:
Dr. Ahmed Shafik wears three-piece suits with gold watch fobs and a diamond stick pin in the lapel. His glasses are the thick, black rectangular style of the Nasser era. He owns a Cairo hospital and lives in a mansion with marble walls. He was nominated for a Nobel Prize. I don't care about any of this. Shafik won my heart by publishing a paper in European Urology in which he investigated the effects of polyester on sexual activity. Ahmed Shafik dressed lab rats in polyester pants.
There were seventy-five rats. They wore their pants for one year. Shafik found that over time the ones dressed in polyester or poly-cotton blend had sex significantly less often than the rats whose slacks were cotton or wool. (Shafik thinks the reason is that polyester sets up troublesome electrostatic fields in and around the genitals. Having seen an illustration of a rat wearing the pants, I would say there's an equal possibility that it's simply harder to get a date when you dress funny.)
Dr. Shafik published five studies on the effects of wearing polyester, and then moved on to something else. If you print out a list of Shafik's journal articles—and you will need a roll of butcher paper, because there are 1,016 so far—it is hard to say what his specialty is. He has wandered through urology, andrology, sexology, proctology. If you ask him what he is, what he writes under "Occupation" on his tax form, he will smile broadly and exclaim, "I am Ahmed Shafik!"
Dressing rats in underpants is not the only good thing Dr. Shafik has done: he has invented not one, but three new methods for male contraception (one of them caught my eye: testicular suspension - i.e. putting one's balls in a sling!)
There's scientific research and then there's scientific research. I hereby nominate Dr. Shafik for Neatorama's Most Awesome Scientist of the Year Award!