A trick I read about in a book is, when you show people your ID, show them your passport, but with a little foam clown nose glued to the picture. Whilst they are checking the ID, put a clown nose on yourself to match the picture. The source I heard this from has apparently received free upgrades and other perks from this. Apparently, airport workers appreciate a good laugh every once in a while.

Disclaimer: I haven't tried it myself (yet).