The Anti-"Bob" is the spawn of NHGH who will emerge in the future to lead the Bozos after X-Day. Since NHGH experiences time backwards, the day when NHGH is born approaches, after which NHGH will cease to exist. And since NHGH is the force behind The Conspiracy in its fight against "Bob", he needs an heir to continue his work after he is gone.
Thus, the Anti-"Bob", the son of NHGH, will take over The Conspiracy and guide it in the days after X-Day in rebuilding Earth and establishing the slackless dystopia of the Bozos. However, the Anti-"Bob" may already exist among us, and may even be a leading member of the Church of the SubGenius, stealing our Slack away, back to the Conspiracy!
Or perhaps we have not yet entered the stage of the End Times when the Anti-"Bob" emerges. There are those who say that when "Bob" was assassinated in 1984, the assassin who shot him was none other than the Anti-"Bob" himself. Others claim that the Anti-"Bob" is just fiction, that the Anti-"Bob" was just made up by SubGenius parents to keep their children from behaving Normal. Perhaps both are correct; after all, they contradict each other, so it makes sense according to SubGenius dogma. Or perhaps all of this is misinformation concocted by the Anti-"Bob" himself to deceive us. We may never know. Especially because the only person who knows the identity of the Anti-"Bob" also knows that revealing the identity means almost certain death for the revealer. Thus the last of the Ten Prophets of "Bob" is keeping his or her mouth shut.