So there I was hitchhiking in Japan. The sun and humidity baking me to a plump doneness. Hours passing by. Thumb openly weeping from a rejection complex. My breaking point come and gone like so many cars.
This guy pulls over in his Daihatsu cargo truck and rolls down his window. Before the tears of joy can even begin to well up in my eyes, he asks me, "Why do you put out your thumb?" "Because I'm trying to get a ride to Kyoto," I explain breathlessly.
He mutters something like "interesting" in Japanese and drives away.
Needless to say, not all gestures are universal. Certainly in that rural area of Japan, most of the drivers probably had no clue why that American-looking dude was sitting on his backpack near tears with his thumb extended.
If you're going to travel abroad, it helps to understand the implications of your gestures:
The "okay" sign
Again, you're almost more likely to get the "okay" sign (index finger and thumb held in a circle with the other three fingers extended, palm outward) from a bunch of kids hollering "Hello!" in a Vietnamese village than you are from an American these days. It certainly seems to have fallen out of favor here at home.
Again, by and large, this is a well-understood American gesture abroad. Where not understood, it mostly just confuses people at worst.
However, in a few countries it apparently denotes a particular body orifice. For safety's sake, steer clear of the okay sign in Germany and Russia. Frankly, I personally take no chances with it anywhere east of Switzerland.
"V" for victory
Despite being invented by the Brits' own national hero, Winston Churchill, the V-for-victory sign poses severe danger of misinterpretation in the U.K.
If you flash the "V" palm outward, everything's hunky-dory - you will have just indicated "victory" or general approval. But, if you flash it with your palm facing yourself, it apparently means something akin to "up yours." Why on earth the reasonable English wouldn't sit down, have a meeting, and jettison one of the meanings baffles me. Call it the Two Fingers Up Meaning Unification Treaty or something.
Many Japanese people hold up the two fingers compulsively in photographs taken in front of tourist destinations. Despite living with a Japanese family for a year (indeed, appearing personally in scores of these photos in front of everything from Ise Shrine to Tokyo Disneyland) I've never understood the habit.
The firm hand grip and direct eye contact so valued in the U.S. as a show of confidence and respect isn't quite as useful in other countries. However, it is pretty widely recognized as the standard American greeting these days. So you're unlikely to get in trouble using it.
However, in other areas you're probably well advised to go a little easy on the firm squeezing bit, which sometimes comes off as overly aggressive. You should also probably prepare for a local-style follow-up, such as a warm hug in Europe and possibly a couple of kisses on the cheek. In South East Asia, gently placing hands with palms together in a prayer-like position, below chin level, is preferable to shaking hands or hugging.
The American-style wave remains something of a universal gesture, again thanks largely to its simplicity and the wide dispersion of American culture. You can scarcely get in trouble waving to someone anywhere you go, so long as you smile. For some reason, the wave is the tofu of hand gestures - it soaks up the flavor of whatever facial expression accompanies it. If you want to look cool in Europe, try waving in their fashion - arm extended slightly upward, hand flapping only at the wrist. The Italians have their own version of this, waving with the arm downward and the palm facing upwards.
Again, this characteristically American gesture remains well understood in most places for its American-ness. Except in a few places, that is, where it could land you in serious trouble - namely Australia and Nigeria. In these countries, it means, again, something like "up yours." Do not use it.
That makes it especially hazardous to hitchhike in those countries American-style. But getting a ride in Australia and Nigeria is seldom a problem anyway given local openness to travelers.
The usefulness of the thumb up in other countries as a hitchhiking symbol remains questionable, however. It is largely just misunderstood and does not affect the likelihood of getting a ride anymore than a simple extended arm.