Usually someone with a mental ability and social skills of a four year old and just as annoying. He or she will not have the wits to operate anything more complex than a point and shoot GUI windows interface to do anything on the Internet. Therefore he or she will use someone's else craftmanship to attempt to committ nasties on people or services such as flooding. The vast majority of their attempts to cause disruption are as futile as trying to get a blonde to drive a Lamborghini on diesel with rocks in its gearbox on the M25 motorway at 8am.
All script kiddies have less of a life than a 110-year old man in a 70-year coma, and often a result of interbreeding in some farm in the Deep South.
They may claim to be hackers, but that is about as true as Sterri having never farted in his entire lifetime.