Stephen Colbert spells out the secret of being an expert on anything in this Wired article. For example:
PICK A FIELD THAT CAN'T BE VERIFIED. Try something like string theory or God’s will: “I speak to God. I’m sorry that you can’t also.” Security experts are in this category: They have security clearances, we don’t. We can’t question the expertise of the NSA because we are not in the NSA.
USE THE WORD ZEITGEIST AS OFTEN AS POSSIBLE. Ideally, you want to find words that sound familiar but people don’t really know their definitions: zeitgeist, bildungsroman, doppelgänger – better yet, anything Latin. But avoid paradigm. It’s so 1994. If you say the word paradigm, everybody knows you’re a poser.