A couple more thoughts on the use of humor in preaching:

Beware of the temptation to stir response by using cheap-shots.  While effective humor is either natural or difficult to pull off, cheap-shot humor is actually quite easy.  It is easy to take cheap-shots at a culture or gender or certain occupations.  It is easy to get a reaction with such humor.  But think very carefully.  Just because people may laugh now, that comment could linger longer than you intended and ultimately become a significant distraction.  I recall one sermon I heard a few months ago.  In the space of two minutes the speaker managed to throw out two quick cheap-shots.  Both got a reaction.  One was at the expense of the president of a nation.  The other was at the expense of the main broadcasting company in another nation.  Both comments were ill-informed.  Both were borderline offensive to the two nationalities targeted.  Both left a bitter taste in the mouth.  Unfortunately for the speaker, those two nationalities formed 90% of his congregation.  Why is it that six months later I remember those one-liners so clearly, but can’t recall the “important” elements of the sermon?

Laugh at yourself rather than at others.  In the example just described, the cheap-shots at other nationalities were only made worse by an apparent unwillingness to laugh at himself or his own culture.  Without making yourself out to be a fool, don’t take yourself so seriously that you elevate yourself over your listeners.  

Where there is no humor, smile appropriately.  A sermon or occasion may not be conducive to the use of humor.  You may be personally challenged in the area of humor.  Or you may be in tough preaching situation, such as preaching through a translator in a foreign culture.  Don’t despair.  Look for opportunities to express joy and delight through well-placed and natural smiles.  God gave us smiles to communicate warmth, affection, connection and life.  Laughter often seasons a sermon effectively, but a natural smile should be a staple element in almost any message.