It's just a new function you can use to have fun with your fellow posters. If someone says something you like, then "high-five 'em". If they say something you don't, then "bitch-slap 'em".
As far as I know, it doesn't affect your standing on CC. It's just something you see underneath your screen name. Also, I believe you can only "tag" a person every hour. There is a time limit so you can't sit there and keep tagging the same person.
I've noticed that some people have really high numbers. People are having fun with it.
Enjoy!