If you're going to lie, then you might as well LIE. Go for the big ones, and change them every time. Make it so blatantly obvious. They'll think you're either crazy, or they'll never be able to tell what's real and isn't.
My suggestions:
- CSI (New York, not Las Vegas)
- Artificially inseminating cows
- Naturally inseminating cows
- Osmosis un-reverser
- Flute tuner
- Astronaut (but the kind that goes underwater)
- Commercial writer. You did the one for McDonalds about the guy who takes credit for stuff he didn't do.
- You work for The Internet, making hard copy backups by hand
- Deprogram people who worship false Guitar Heroes
- Zeppelin pilot. Just the single engine ones, since you haven't clocked enough airtime for your LED license
- Card counter