If you participate in this holiday, you'll almost certainly get fired and might even get arrested. And I'm not sure saying, "But the Internet says it's a holiday" will hold up in court.
Apparently, today is National Slap Your Annoying Coworker Day.
There's no word on whether anyone's ever ACTUALLY taken advantage of the holiday as a chance to slap a coworker . . . so hey, you could be the first.