As Dennis Miller once noted in his book The Rants, kids think farts are hysterically funny. That's because farts ARE hysterically funny - at least to hear.
So, a line of toys kids are asking for this year for Christmas capitalizes on that. They're called Buttheads, with butts for heads... and they let out fart noises. Think of them as advanced whoopee cushions. They're come as action figures, in everything from a deep-sea diver to the Grim Reaper.
You can find them at some stores, on Amazon.com, and elsewhere. Because hey, grown-ups with immature senses of humor - which I proudly consider myself a part of - might be interested in these too. You know, for the workplace, a Secret Santa gift, something for your spouse... the possibilities are endless!