I thought it was just me. But according to a study published this month in the British Journal of Urology International by a University of California San Francisco urology resident named Herman Singh Bagga, an estimated 17,616 people wound up in U.S. emergency rooms between 2002 and 2012 because they caught their genitals, almost always penises, in zippers.

If you’re giggling right now, you’ve never done it.

And you’ve probably done it. Zipper injuries are the single most common cause of penile injury in adult men reporting to emergency rooms, Bagga explained in an interview, followed by bicycles. (In small boys, the most common cause of penile injury is a toilet seat slamming down when the child is urinating – “you’d be surprised how many little boys rest their penises on the rim,” Bagga said -- followed by zippers.)

OK, so it’s a little funny in a Three Stooges kind of way, but a careless zip of the pants can be serious. While permanent damage is rare, Bagga said, zipper entrapment has led to surgical intervention such as undesired circumcision. A more common consequence is infection.

Lots of bacteria can be found in that area, and if the skin breaks, “it’s important once you get it out from the zipper that it’s washed well, and you use a little antibiotic ointment. Keep an eye on it. That’s another reason to solicit medical attention.” In his study, which used data from the National Electronic Injury Surveillance System, Bagga and his co-authors found 11 cases of penile cellulitis (a bacterial skin infection) or abscesses.

Mainly, he said, “this is a pain issue. It can completely ruin your night.”

Bagga wanted to conduct the data analysis because, while there has been a developing body of literature on how to free a trapped penis – using everything from screw drivers to wire cutters -- many emergency department physicians don’t expect these cases and so don’t familiarize themselves with the techniques. Bagga confessed that he’s experienced the penis-zipper interaction and he suspected many more men did than is commonly appreciated.

“Nobody ever looked at it,” he said. “Our goal was to highlight the real incidence.”

Preventing penile entrapment by a zipper wasn’t an issue until 1913 when the modern zipper made trouser dentata common. Today, paying attention is the best way to prevent it. Wearing underwear helps, too.

In case of an unfortunate zip, Bagga advised, it’s best to try to free oneself gently by backing the zipper down. If that doesn’t work, don’t struggle. Head for the ER. And don’t be too embarrassed. You’re not alone.

Brian Alexander is co-author, with Larry Young Ph.D., of "The Chemistry Between Us: Love, Sex and the Science of Attraction,"now on sale.