"Parents, shield the eyes of your children! Virgins: Pay attention!"

John Barry clearly enjoys presenting his invention to a wide audience. It's a penis-function test that anyone can perform at home with little effort, expertise or expense.

All you need is a ring of stamps and perhaps a little imagination.

It was as far back as 1979 when Barry first invented the test, with two fellow physicians, Bruce Blank and Michel Boileau.

And now — almost 40 years later — the three Americans have been awarded the Ig Nobel Prize for Reproductive Medicine. It's a parody Nobel Prize that honors achievements in science "that make you laugh and then think."

"Our test reveals whether, when a man sleeps, he has normal erections or not," Barry tells DW.

A man has anywhere from one to five erections each night. It happens automatically when he dreams — "regardless of the content of the dreams."

Men who don't have spontaneous erections during sleep probably have a physical problem, Barry says. "They may have diabetes or a hardening of the arteries."

But if the penis does function properly during sleep and only fails when … others would be aroused, the problem is in the man's mind.

The stamps can apparently help determine which it is — a physical or psychological problem.

This is how it works

Take several stamps separated by perforation, wrap them once around your penis and glue the two ends together.

If you're using "old-fashioned" stamps, lick the ends to make them stick together, and for non-sticking stamps, use a small piece of adhesive tape, Barry advises.

In an interview with DW, the three Ig Laureates demonstrate the test using two of my fingers as a substitute for a penis.

"Now, you have to imagine that during an erection the penis not only gets longer, but also thicker," Bruce Blank kindly points out.

And it's the thickness that the ring of stamps breaks open, most likely at one of the perforated seams.

The evaluation process in the morning is simple: Check to see whether the ring of stamps is broken.

Four stamps for an average penis

Presenting his penis-function test at his Ig Nobel Prize lecture at the Massachusetts Institute of Technology (MIT) in Cambridge, Barry shows drawings of a penis wrapped in a ring of stamps — and the audience bursts into laughter.

"The average Caucasian penis only needs four stamps," says Barry, answering a question from the audience. And, no, the motifs on the stamps are irrelevant, as is the question of who licks the stamps before putting them onto the penis.

At the end of the 1970s, there was only one way to test a man's potency. It involved a mercury strain gauge.

A band was wrapped around the penis and a machine registered whether the "member" expanded or not. The test cost US$500 (€424) and lasted three hours.

"Our test costs only 12 cents for three consecutive nights," Barry says — if you use one cent postage stamps, that is.

Stamps are better than fishing line

So, what's the patients' compliance like? Excellent, says Blank.

"They want to find out whether the problem is in their head or in their penis, and what therapy can help them," Blank says. "So they weren't too shocked when we introduced this test."

Before they settled on postage stamps, the researchers also experimented with adhesive tape and fishing lines. But the latter in particular, was "quite uncomfortable."

One question remains and that is why they were only awarded the Ig Nobel Prize now, 38 years after they published a paper on their test.

Barry explains it this way: "It stood the test of time."

The stamp test has been cited in Playboy magazine and in the TV series "Sex & the City" — so it's got to be worth an award, right?