When you provide the comic relief for the Leader of the Free World, the line between funny and weird can get a little blurry. Consider the extraordinary experiences of Mark Katz, the in-house humor writer of the Clinton White House, whose job was to produce the president's comic response to the crisis du jour. For eight tumultuous years, he wrote Bill Clinton's annual series of humorous speeches to the Washington press corps - those rare evenings in the nation's capital when the president trades in his bully pulpit for an open mike.