Million Dollar Ideas that--with faith, perseverance, luck and almost no cash--paid off: from the Pet Rock, the Slinky, the Hoola Hoop, and the Frisbee to assorted offbeat enterprises of some current notoriety. Shook, a success-story maven (The Entrepreneurs, etc.), sees a great future alike for Eastern Onion 'grams (""jazzy, sexy, funny one-man-band performances""), the Erotic Baker (Tiny Titties, of chocolate; penis and vagina bread), Babyland General Hospital (soft-sculpture infants, for ""adoption"" by adults), the Toughman Contest (local amateur slugfests), and Celestial Seasonings (#1 US purveyor of herb teas). The single plain-talker in this odd lot is Rent-a-Wreck's Dave Schwartz--who avoids complaints (""Really, I'm into no grief"") by not promising perfection. It's the national crazes, though, that make the great stories. The Pet Rock started as a one-liner in a Los Gatos, CA, bar. (""I don't have any trouble with my pet,"" said advertising drop-out Gary Dahl. ""I have a rock."") The Slinky actually did walk off a shelf into the life of young mechanical engineer Richard James--who was never the same thereafter: wife Betty was left with six children and a tottering business. The Hula Hoop went nowhere for Wham-O partners Richard Knerr and Spud Melin until they got kids to demonstrate how it worked. Ditto, the flying saucer/Frisbee disc. All these last--and Mood Ring promoter Marvin Wernick, the only old pro on hand--dilate thoughtfully on the anatomy of a fad. The Slinky and Frisbee folk also take rightful pride in the simplicity and universal appeal of their creations. So it's not all promo: at least a third has lasting curiosity value.