Know any good jokes?

Brian's doing an internship this summer and was told by a friend (that did the same internship several years ago) that its not uncommon for a summer intern to be called upon before a meeting to tell a joke (interesting, I know). The joke would have to be totally clean and appropriate for staunch businessmen and women. We don't tell jokes all that often, so we don't know any. If you have a good joke, will you post it as a comment? Thanks!