Happy National Blackmail Day!

According to someone online, today is National Blackmail Day. I can't figure out what exactly this means. Are we supposed to go learn other people's deepest secrets to use for our own advantage? Or are we supposed to go ahead and cash in on the secrets we already know about other people? Holidays like this just give me a warm happy feeling, you know?

There are definitely one or two people out there I'm staying the hell away from today.