Most of us are well familiar with the customs and idiosyncrasies of the area where we live. In fact, we probably don't think much about them until we see someone from another area of of the USA or a visitor from abroad say or do something that is just plain wrong.
What poses a problem for us, however, is when we travel and find ourselves, often quite innocently saying or doing something that turns out to be very embarrassing.
For example, long gone are the days when you just needed your driver's license to go into Canada. Today you need a US passport if you're a US citizen. Without it, you'll be turned away at the border. That mistake, can be pretty costly if you've paid for a vacation in Canada.
If you're headed to Barbados or the British Virgin Islands, don't make the mistake of renting a car and drive on the right. You'll likely have an accident since they drive on the left. And if you're headed to Bermuda, you won't be able to rent a car at all as a non-resident.
If you're heading to India, keep your feet to yourself. Don't point them at people or touch anything with them. Your feet as well as your left hand are considered unclean.
Even when you go to Hawaii, there are plenty of things that you should not do. For example, keep your hand away from that car horn unless you want to get some nasty gesture from those around you.
About.com's Travel Guides have it all covered for you across the globe. Thanks to our Guide to Honeymoons / Romantic Travel, Susan Breslow Sardone, for putting all of the details together in her feature Don't Do That! I recommend that you bookmark her feature for reference on any future trip whether it be in the USA, Canada or overseas.