Word is Bomb: A phrase used to stress the significance of what is about to be said or what has just been said. The word bomb suggest that this person's 'word' or whatever this person says is as serious, important and shocking as a bomb would be.

When you eat dirt for the first time and leave your family to build a shack in the woods

The coolest catch phrase ever invented, meaning word, worbs, strops. It originated in the streets of dorchester mass. Use Word is so bomb for emphasis, use on that to mean word is bomb on a certain object.