Clackers, lawn darts, melt 'em yourself lead soldiers, Pez guns, Snurfers, the Jesus doll, the original Teddy Ruxpin, merchandise tied to Hollywood megaduds: For every Cabbage Patch Kid or Tickle Me Elmo, there has been a holiday gift that has either threatened the health of its recipient -- or the bottom line of its maker. While Santa is only human, and thus entitled to an occasional off day, the jolly old soul has over the years delivered a staggering number of ill-conceived, shoddy or downright lethal playthings to the youth of America. The creation in 1972 of the Consumer Product...