Keep in your possession as you pass thru Customs:
10. A genuine hangman's noose.
9. Large amounts of Monopoly money.
8. Realistic drawings of Margaret Thatcher, in the nude. (Change as appropriate, depending on the country you visit).
7. Several pounds of white flour in sachets placed inside your shoes. (Claim that it is flour, but look very nervous).
6. A thick folder with the title "How to Fool Customs Officers" in large letters. Make sure all the pages are blank.
5. A book by the title "How to Start a Trotskyst Revolution." (For added effect, speak with a thick foreign accent and wear a three-day growth of beard).
4. Half a dozen, very real-looking, but completely fake, hand grenades (together with the above book, for additional impact).
3. A large number of used condoms, tied in pink and blue ribbons.
2. A half-eaten pastrami sandwich, wrapped in a Playboy centerfold.
1. A dozen bottles of vodka, filled with water.