According to a study by smellologist Alan R. Hirsch, grapefruit ought to be the hot new scent in women's perfume. That's because in a recent experiment, he found that men who were exposed them to the smell of grapefruit tended to judge the women around them to be five years younger than they actually were. As the Chicago Sun-Times reports:

In his study, 37 people, after wearing a surgical mask infused with various odors or no odor at all, were asked to estimate ages of people in 108 photos. On average, the men in the study underestimated the age of the women in the photos by five years. A later study using real people instead of pictures had similar results.

Even more amusing is the fact that "Hirsch got the idea after conducting a similar study that found that men sniffing a mixed floral scent on average believed women were 12 pounds lighter than they actually were."

Judging by his web site, Hirsch spends an inordinate amount of time investigating which smells will get us to do the nasty. In another recent experiment, he tested the effect of various combination odors on men's penile blood-flow. His findings? "Lavender and pumpkin pie" was the ultimate scent of passion, causing a 40% increase, while the runner-up -- with an increase of 31.5% -- was a subtle blend of "doughnut and black licorice".

Doughnuts mixed with black licorice?

(Thanks to Peter Sagal for this one!)