Some topics to be careful with:
- Popular Culture: Most scientists even many American scientists have no clue what occupies the minds of most Americans. Even a Michael Jackson joke would likely fall flat at our conference. A Star Wars joke might work on a majority of our crowd but too many of them feel that anything that is popular should be ignored. One exception is children's popular culture: Not that anyone likes Barney but you can't avoid him, especially if you have young kids.
- Politics: Since our field lies in such a narrow band in American politics, political jokes are fine as long as they sit in this band (i.e. making fun of Bush and his cronies). But a seemingly harmless joke outside this band will be considered "offensive". I once talked about a paper by Allender and Gore and said "but this is not the Gore that invented the internet." Didn't go over very well.
- The P versus NP problem: Some things are too important to joke about.