Passport pussy is all the great sex a woman promises a man if he takes her on a trip outside of the country. In this case the man generally pays most of or all the associated expenses of the trip.
Woman - You should take me with you to Cancun. It will be cheap. I can share a room with you. Just think of all the great sex we'll have together.
Man - Nah, I am not paying for any Passport Pussy!