From Berkeley to Boston, Wednesday counts as the high point of the comic-book purveyor's week; it's the day when new shipments--and the customers who crave their contents--arrive. Hence, the preceding day tends to run a little turgid, except at Big Brain, whose "Tuesday Triple Threat" monkey-wrenches this otherwise-ironclad law of geekonomics. The deal? Buy two items from the shop's generous assortment of toys and get a third of equal or lesser value free. You can pick up, say, a pair of Simpsons interactive play sets and walk out with a sparkling white Comet the Super Horse plush toy gratis. But bonus baubles are but a mere fraction of Big Brain's bait-and-bait-again strategy: The store offers mugs, watches, statuary, coasters, trading cards, CDs, and videos, as well as a constellation of comics ranging from Babar-innocent to the nautical naughtiness of the Eurotica imprint. Proprietor Michael Drivas even maintains a well-selected short shelf of books with few or no pictures, including a handful of hard-to-find McSweeny's titles and that landmark of medical scholarship, The Thackery T. Lambshead Pocket Guide to Eccentric and Discredited Diseases.