Yeah, he wrote the script and acted in it. He had creative control, and it's just a damn good film. The sequels suck, but 95% of sequels do.
Actually he wrote and directed the first half. The vampire part was some Rodriguez or Martinez fellow, i beleive.
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Gas and masturbation are highly unlikely to be connected with each other. Have you tried to stop masturbating? Has the gas subsided as a result? Perhaps you could try the same experiment by increasing the times you masturbate daily. Do you notice that the gas is increasing?