Can I get in trouble for lying on internet forums?

So, being familiar with internet forums for quite a long time, I realize that for the sake of giggles, you can pretty much lie about anything. But sometimes, these lies are taken seriously by forum members, and sometimes, they "attempt" to pursue "legal" action. For example, I tend to troll forums for reactions. I claimed I killed a guy. Needless to say, Moderators were trying to trace back my IP address and report it to the "proper authorities" (this being a police department across the country, lol). I realize that since it's a private board, they can do whatever they want. Oh yeah, since they got my IP address from my private university....would they go as far as to contact them and attempt to defame me somehow? Can I do what I want on the internet?