Don't forget to tell them you want to converse in English. In Hong Kong you would never beckon someone by putting your hand out and curling your index finger back and forth. When speaking to foreign audiences you must check your humor carefully so you don't accidentally offend someone. That doesn't mean you can attempt to joke about the same subjects in your presentation. Even if your speaking humor is OK, you need to become familiar with other customs in the country in which you are speaking.
Customs are quite different around the world.
It is easy to make mistakes when you are in a totally new environment. You'll never get the audience to laugh if you accidentally do something offensive. The Do's and Taboos of Body Language Around the World by Roger Axtell. This book gives lots of information on things to do and not to do in public when in a foreign country. In Columbia if you wanted to show the height of an animal you would hold your arm out palm down and raise it to the appropriate height.