Bombshit is the marriage of the the terms "the bomb" and "the shit" only to emphasize the "bombness" and the "shitness" of oneself. This term should be used when the titles "the bomb" and "the shit" are not suffiecent because they do not capture the true quality of the person in the situation. It should be only used sparingly in order to preserve it's effect.
"Wow Greg! You are the bomb, no the shit, no the BOMBSHIT!"