My stay in Chicago included a walking tour of the architecture of some of the city's most famous buildings.  One building had a statue on top.  Most people weren't aware of it because they normally wouldn't be looking up.  (You can always tell the out-of-towners, they are looking up at all the tall buildings, while reminding each other to not look obvious:  "Act like you're from around here.") 

When we use humor in our speeches, we achieve this same phenomenon:  we offer something unusual, special, and memorable.  Just like the statue at the top of that building.   Which by the way, had no face on it.  The sculptor figured that people could see the statue, but wouldn't be able to see it that well.   

What can YOU add to the architecture of YOUR next speech?