We had an interesting time with a puppet show when we were traveling in England with a choir tour. The puppet show was just a cute little addition for the kids to watch while we were singing. Unfortunately, we didn't realize that certain hand gestures have alternative meanings in other countries. Our puppets had one song where they made the peace sign with their fingers and danced. At our first show, the audience was appalled. Several parents removed their children and we were really confused. The pastor of the church (yes, this was at a church which made it so much more embarrassing) pulled us aside and explained that the particular hand gesture we were using does not mean peace in the UK.
A friend of mine once got in trouble with his mom. She gave him a long lecture about whatever he was in trouble for, and he nodded his head and said 'yes, ma'am.' When she turned to leave, he flipped her off. He hadn't realized that she had rearranged the furniture that day. There was a new mirror on the wall, and she had seen the whole thing.
I'm surprised he lived to tell the tale, honestly. He learned an important lesson about non-verbal communication that day.
In the culture where I grew up, a woman would only play with her hair while talking to a man if she was interested in him. This, of course, is not the case in the United States. When women from the US would come to the island where I lived (like as Peace Corps volunteers) they would find themselves giving the wrong message to men without knowing it. I don't know how funny they thought it was...