I came across this posting from the Language Log and thought about one of the main minefields of foreign travel, foreign language (though I guess some travels actually involve real minefields, I'll stick with the metaphor). In the post, the author describes being duped in Taiwan into thinking that a certain expression meant "thank you." Later, he learned he was inadvertently flirting with everyone around him.
Megan and I had a similar experience at the fish market in Zanzibar. A kind man decided to coach us on the way people shake hands in Tanzania and Zanzibar. They lock hands and place thumbs together. Slowly, they slide the thumbs past each other and then release the handshake. Then they make a fist and knock knuckles. This man added an additional step: after the handshake, he suggested we should pound our chest and raise our fist in the air. No problem. We had fun making the handshake, and we felt like we were learning some inside information.
Later, we encountered some tour guides in a local bar near our hotel. We chatted with the guides for a while before displaying our new handshake. The guides erupted into laughter. Apparently we had learned the "pot smoker" handshake.
Megan tells a similar story from her time in Spain. A Danish friend taught her an expression that supposedly meant "hurry up, let's go." When she tried the word out to her other Danish companions, she soon learned that she had been tricked into announcing her overwhelming, passionate desire for the other members of the group.
Megan tells another great story from Spain, suggesting that the confusion can be mutual. She arrived home from a day at school to find the mother of her host family fairly distraught. The mother began telling a story of her friend who had just died. Megan, still working on her language proficiency, thought the mother was telling the story of a dead chicken, and replied, oh-so-sensitively, in Spanish, "That's a good thing. It will taste better that way." Cannibal.
Point being, people like to abuse the naivete and excitement of travelers. The author of the Language Log suggests avoiding using language you don't understand. I take a different approach. I say use it and be fooled--those bits of entertainment to your local hosts may compensate for other goofs that might not be so funny.