The other day I bought my son a pack of miniature whoopee cushions that I found on sale at Target.
Let me just say that I had the most amusing half hour watching him try to position his hind end on those tiny little balloons (and believe me, it took some maneuvering on his part). And then the pure joy that emanated from him as tiny puffs of air were released from the general vicinity of his rear, while he gleefully exclaimed "Mommy...I tooted!"
Of course, some of the hilarity on my end may have been a result of constantly blowing those damn things up, while inhaling the toxic fumes of the rubber/vinyl??? they are made of.