Kablah is a klingon word, used by several klingon's on star trek next generation.
kablah is a word with many meanings. it can mean "hate", "kill", or "destruct" - depending on how used.
generally it's a curse-word and it should not be used around klingons, as they will take it as an invitation for a "duel till death".
Mel Gibson also uses this term when scaring strangers away from his propertys or when trying to kill somebody - this happens to the fact that all the world knows, that Mel Gibson is half klingon, half insane, half manbearpig.