We’ve all heard of tricks to gauge a man’s penis size without seeing it - the size of his hands, feet, weapons - but Korean researchers have now determined that the ratio between a man’s index and ring fingers is a good indicator.

Thomas H. Maugh II of the Los Angeles Times describes the research of urologist Dr. Tae Boem Kim and his colleagues at Gachon University who studied 144 male patients over the age of 20 who had come in for surgery. They measured the ring and index fingers on the right hand before surgery and then the length of the penis, flaccid and “stretched as much as possible” after anesthesia (the team wrote that stretched and erect lengths correlate).

The result, writes Maia Szalavitz of Time magazine….… listen carefully, size queens: is this: “those with a lower ratio, whose index finger (or second finger, 2D) was shorter than the ring finger (or fourth finger, 4D), had a longer stretched penis length, which is well correlated with erect size.”

And yes, there’s more science to it.

“Although it seems like it might be coming out of left field it’s not,” Maugh writes. “A variety of studies suggests that the ratio of the two fingers is determined by prenatal exposure to sex hormones, both testosterone and estrogen. It is not unreasonable to assume that penis length might be.” Click both stories for other studies on what index-ring finger ratio might indicate.

And watch for more keen-eyed girls asking guys for a high-five.