A little boy and a little girl, both about eight years old, were playing in the sandbox. Unexpectedly, the little boy farts, causing a little sand between his legs to shift. The little girl notices, and squeals with laughter. "How'd you do that?" she asks. "Easy," he exclaimed, "I just farted." "Can I try it," she asks? "Sure," he says, "anybody can do it She concentrates as she strains and grunts. Suddenly, there's a huge explosion, the sides of the sandbox fly off, all the sand flies out, and the little boy is thrown 20 feet, landing up against a tree. He groggily gets to his feet, runs back to where the little girl is. He finds her laying on the ground, out cold, flat on her back, spread eagle. Curiously, he lifts up her dress, peeks underneath, and loudly exclaims, "Just what I thought, dual exhaust!"