This theory, or assumption or whatever it is, has no effect on current or upcoming events in Lost at all, but I don’t know if anyone else has thought of it. It actually seems pretty obvious now, so it’s most likely that others have thought of it.
In Hurley’s season 2 episode, “Everyone Hates Hugo”, he spend the whole episode with his friend Johnny, he also goes to see a girl that he likes named Starla. After rewatching this episode I believe that both of those characters are imaginary.
We know that Hurley has an imaginary friend named Dave (seen in the episode “Dave”), he represents Hurley’s self-loathing and self-destructive inner voice. He speaks just like Hurley and follows him around wherever he goes.
Similarly, Johnny speaks exactly like Hurley and follows him around. What really convinced me that he was imaginary was when Hurley quit Mr. Clucks Johnny immediately did to. He quit offscreen with no motivation and no plan as to what they were going to do next. He doesn’t act like an independent human, he acts like Hurley.
As for the girl Starla (it’s hard not to sound like an awful person here) Starla probably wouldn’t like Hurley as much as she did. And if she did like him as much as it seemed, then why did she just leave as soon as he got money, it seems a little suspect.
The end of Johnny and Hurley’s relationship also comes at a time when Hurley’s life changes dramatically. Hurley wins the lottery and suddenly Johnny and Starla abandon him. He was afraid that his life would change for the worse and it did.
I believe that Johnny and Starla represent a kind of mediocre contentment in Hurley’s life. So when Hurley wins his money he knows that everything is going to change. His old life is over, and as mediocre as it was, he was pretty happy with it.