Best reply on this forum ever ... I almost wet myself when I read this hahahaha!!!
Unless you're talking about actual psychopaths? In which case, there's no way to block them unless you sell some sort of fingerprint scanner with the game that's tied into mental/criminal records. BUT OMG THEY'RE PSYCHOPATHS AS IF THEY COULDN'T GET AN INNOCENT PERSON'S FINGER WHY DIDN'T ANYONE THINK OF THIS?!?!