• Celebrate making it over the hill.happy birthday image by Ewe Degiampietro from Fotolia.com
  
  Many elect to turn the celebration of a 40th birthday into a playful over-the-hill celebration. Poke fun at the aging birthday boy and remind him, in jest, that the best years of his life are behind him. By decorating your party in grim hues and making continual reference to the honoree's advanced age you can create a humorous party that will be enjoyed by all.
  
  

Loads of Black

• Make black the dominant color by draping decorations over every surface you can. Cover tables with black tablecloths, hang black streamers from the ceiling, blow up and hang black balloons. If you want to add another color, mix in some somber gray to create a generally dreary mood for the event.
  
  

You Are Older Than...

• Create an informative display that demonstrates just how old the honoree is by setting up a "You Are Older Than..." board. Gather a list of products or people that the birthday boy is older than. To find this information quickly, peruse an invention timeline, like InventionReaction.com. Print out images of the objects or people you select, and place a note next to each indicating when that object was invented or person was born.
  
  

When You Were Young...

• Create a price comparison by covering a table with an array of common goods. Include popular grocery staples like a gallon of milk, a loaf of bread and a dozen eggs. To gather this information quickly, visit ThePeopleHistory.com. On this site, you can download an information sheet, containing prices and events, for whichever year your honoree was born. Cut card stock into rectangles, and fold the rectangles in half to create a tent that stands on its own. On the outside of each tent, write the name of the product, and a note that reads "Today this product costs:" followed by the current market price. On the inside, write, "When you were born, this product cost:" followed by the price of the good when the honoree was welcomed into the world. The birthday boy and guests alike will enjoy seeing how much times have changed.
  
  

You're So Old Joke Competition

• Ask party guests to come armed with zingers to aim at the birthday boy. On the invitation, invite guests to find "You're so old..." jokes. As guests enjoy cake, allow them each to tell their joke. Offer a prize for the party guest who finds and recites the most humorous joke.