Have you ever wondered why some people never seem to "get" your jokes? It could be they are actually not physically able to process sarcasm.
A recent study at the University of Haifa in Israel used high-tech scanning equipment to track what happens in the brain when people were presented with sarcastic statements, such as "Hey Joe, don't work too hard", said to Joe when he was obviously relaxing. Some people recognized it as sarcasm and either laughed or became defensive, and others did not. Lack of response was most pronounced in autistic people with no discernible ability to process inconsistent messages.
What does this mean to you? It reminds you that when presenting, it might not be safe to assume that everyone will appreciate your witticisms. Inappropriate humor can backfire on a presenter. If you don't know how your audience will respond, don't take chances.
When in doubt, keep it positive.