According to a study published this month in the British Journal of Urology an estimated 17,616 people wound up in U.S. emergency rooms between 2002 and 2012 because they caught their penises in zippers.
Let the truth be told, zipper injuries are the single most common cause of penile injury in adult men reporting to emergency rooms. While permanent damage is rare, zipper entrapment has led to surgical intervention such as undesired circumcision. (Just one more reason to have a circumcision even if you are not Jewish!)
Bottom Line: In case of an unfortunate zip, it’s best to try to free one’s penis gently by backing the zipper down. If that doesn’t work, don’t struggle but head for the nearest ER. And don’t be too embarrassed. You’re not alone you’ve got over 1000 buddies who have been there before you!
Dr. Neil Baum's Urology Blog 