Script kiddie
A derogatory term for a clueless and malicious hacker. Usually used specifically to refer to someone who doesn't really have much in the way of visible skills themselves, but simply looks around for a rootkit and then tries to apply it to everything in sight.
Script kiddies would not be particularly dangerous without black-hats to supply them with interesting things to do. They are, however, becoming more and more of a problem as the years go by and the internet becomes more and more all-pervasive - they magnify the scope of any given security breach by many orders of magnitude, both because of their sheer numbers (it's a lot easier to be a script kiddie than a black hat) and because while a real black-hat isn't likely to attack a system that he doesn't have a real use for, a script kiddie will try to "pwn" anything and everything in sight.
It is generally considered a DIRE insult to refer to someone as a script kiddie.
Contrast and compare white-hat, black-hat. These are not FreeBSD-specific terms, but they're included here because the terms are relevant to any security discussion.