Youtube has many videos on how to beat polygraphs. My friend Willie has only been asked to take one, and he showed up with a machete and a live chicken and a few candles -- when asked why, he said, "You invoke your god, I invoke mine. I'll just use this desk, here." He put the chicken on the desk, and over protests, held it in place as he got out the machete, and was chased from the room by an outraged administrator. His response to his boss? "You should pick calm, thoughtful people next time."
Further notes here.