Mary Roach goes all the way for scientific research.
In 2007, she had sex with her husband while a British doctor waved an ultrasound wand over their private parts testing their genital responses to the soundtrack of "Les Miserables."
Her compliant husband — innocently lured to London with the promise of "an all-expense paid trip" and a day at Stonehenge — rose to the occasion with a dose of Viagra, she says.
"It was a weird mix of medical procedure and sex," Roach, who took copious notes throughout, told ABCNEWS.com. "Ed said afterward, 'I was really creeped out that I did this.'"
It was all for the sake of Roach's new book — "Bonk: The Curious Coupling of Science and Sex" — which reached #10 on the New York Times bestseller list this spring.
"He's such a good person," Roach said of her husband, a graphic artist. "Mary needs this for her book, I will ejaculate."
Not since Masters and Johnson wrote "Human Sexual Response" in 1966 has the physiology of sex been explored in such detail. Until their groundbreaking study with married couples, researchers would "simply, quietly do it themselves."
In the case of London's Dr. Jing Deng, who studied Roach's sexual response, he wanted to capture "real-time, two-party human coitus," but he couldn't find takers. She volunteered.
"It's one of those things you agree to, and you're not really thinking it all the way through," said Roach. "If my husband had been thinking it through, he would have said, 'No!' The burden of performance was on him."
She even participated in an arousal study at the University of Texas at Austin. "It was not particularly demanding," Roach said. "I had to sit in a chair in a room with no pants on with a seismograph and was a control subject watching porn."
The 49-year-old is no stranger to strange topics. She has written about Eskimo food, flatulence, vaginal weight-lifting, carrot addiction and amputee bowling leagues. Her two previous books also explore oddities with humor: "Stiff: The Curious Lives of Human Cadavers" (2003) and "Spook: Science Tackles the Afterlife" (2005).
Curious is the operative word. Roach stuck her nose in a Taiwanese lab where penises culled from cadavers were skinned like snakes in an effort to find a cure for impotence. She also witnessed a Danish pig farm where sows were stimulated with vibrators to improve their conception rates.
Roach has discovered the term "boner" is also a misnomer. Unlike dogs and other mammals, men don't have penile bones. The walrus sports the largest one, and Inuits use it for war clubs.
It took Roach two years to research and write the book. "Sex is so intimate and personal and emotional, and science is so clinical," she said. "How you bring it into the lab and study it is a conundrum."
The daughter of a Dartmouth College professor and a secretary, Roach was raised in New Hampshire, where she "didn't quite fit in" at the local high school where most kids were "jocks."
She went to Wesleyan University in Connecticut, which has a reputation for open-minded inquiry. [At one time, the college was proud of its all-nude dorm.] "It gave me a kind of ridiculous hubris to do whatever I wanted," she said.
Roach's writing career began as a part-time PR person, working next to the Gorilla House at the San Francisco Zoo. Off hours, she wrote humor columns that appeared in national magazines and even on "The Colbert Report."