Rubber Chocolates

• Present a box of rubber chocolates to the guest of honor with a known sweet tooth. Not only will the recipient be in for one big surprise when he bites down on the rubber, but the birthday honoree can "share" the rest of his chocolates with other unsuspecting guests at the party.
  
  You can also use the rubber chocolates to decorate the guest of honor's piece of birthday cake, cupcake or pie. (One place to find chocolates like these is http://www.thegag.com/a1391.html.)
  
  

Exploding Pen

• Wrap up an exploding pen in an elegant box. As soon as the recipient opens the gift, ask her to open the lid to ensure that it writes--the pen will explode the moment the lid is taken off. Be certain not to use this gag on a person with a weak heart or serious medical condition. (One souce is http://www.prankplace.com/fun_explodingpen.htm.)
  
  

Instant Hair Hat

• Cut fuzzy gray fabric into a circular shape and attach it to a Velcro-backed sun visor. Secure the faux hair into the visor with fabric glue. Allow to dry. Present it to your balding forty-year-old on his birthday. You can even expand on the gag by presenting the instant hair hat draped over a plastic skeleton head or bald man Halloween mask.
  
  

Retirement Clock

• Give the birthday man or woman a retirement countdown clock. The retirement countdown clock will count down the days, hours and seconds until the person's retirement, from the year 2049 and down.
  (To see one option, visit http://www.countdowntime.com/main/proddetail.cfm/prodid/3100.)
  
  

Regularity Drink

• Purchase the largest bottle of prune juice you can find and use a ribbon to attach a champagne glass to the front of the bottle. Insert a folded card into the glass that reads "In case of irregularity, drink immediately."
  
  You can also nonchalantly serve the guest of honor prune juice disguised as a glass of wine. Propose a toast to her health and watch the room erupt into a fit of giggles when the honoree realizes what beverage is really in the glass.
  
  

Gift Tie

• One 40th birthday gag gift tie reads "Celebrating the 22nd Anniversary of my 18th Birthday." To expand further on the gag, you could present the tie wrapped around a plastic battery operated light up skeleton. This product can be found at http://www.zazzle.com/40th _birthday_gag_gift_tie-151479244031967342.
  
  You can also purchase T-shirts, mugs and other novelty memorabilia with the same message on them.
  
  

Survival Kit

• Construct an old-age survival kit for the birthday guest of honor. Include such items as wrinkle cream, denture adhesive, adult diapers, fiber, a cane, reading glasses with bifocals, Ben Gay, Ex-Lax, a bag of prunes and gray-coverage hair color.
  
  Decorate the box to look like a coffin and position a miniature funeral wreath on top of it. Wrap the box in bright, festive birthday paper to completely catch the guest of honor off guard.