It's a "leap second", actually. A one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the men solar time. The flap about that is, a couple of years ago when the leap-second was factored in, some webservers didn't know how to handle it and had some problems. It happens every couple of years or so. There are still some nutbags though, who think the leap-second is tantmount to the "Y2K" doomsday scenario, which, at the time, was one of my greatest LOLs in life. While depositing a paycheck one week, some guy in line behind me at the bank, told me to withdraw all my money to prepare for "the end" that next week (as it was going to be the year 2000) I laughed in his face.