When it comes to unwittingly insulting a representative of a different culture, then the Americans are holding the championship. As already mentioned, most Americans do not have passports. They believe that the rest of the world thinks in the same way as they do, and wants to be like America. In the picture you see President George W. Bush, who raised his hand in the welcome gesture of the Texas football team, of which he is a fan. The index finger and little finger here symbolize the horns of a bull. This gesture is understandable to most Americans.
Traditional American football gesture in Italy is considered a cruel insult for which you can go to jail
In Italy, such a gesture means that the man is a cuckold. In 1985, five Americans were arrested in Rome, who, having learned that the Texan team had won the next match, arranged joyful dances with similar gestures on the territory of the Vatican. Naturally, such gestures made the most unfavorable impression on the Pope.

Summary

People prefer to deal with those in whose society they feel calm and comfortable. Sincerity and good manners play an important role here. When traveling to a foreign country, try to reduce the number of gestures used, at least until you find out how much local people attach to them. In order to better understand the body language of a particular country, take a few foreign films and watch them with the sound turned off. Do not read the subtitles. Try to understand what is happening on the screen. Then watch a movie with sound or read the subtitles to see if it’s correct.

If you want to be polite, but do not know how to do this, talk to the locals and ask them to explain the meaning of the basic gestures to you.

The misinterpretation of common gestures leads to awkwardness. Before making any conclusions about the interlocutor's gestures, take into account its origin.
If you often travel abroad, we recommend that you read Roger's Akstella's book Gestures: Body Language Around the World. Axtell describes more than seventy thousand physical gestures and their interpretations in various countries of the world. His book will help you deal with representatives from other countries.