Almost every book group is happy enough with a big bottle of kinda-fine Merlot. But some book discussions scream for cocktails, really glamorous ones with lemony bits and infused vodkas and lots of non-essential shaking. If nobody in your group can answer one key question—what are bitters, anyway?—it's time to bring in a bartender. Call a training school or a caterer, or just ask the guy making your drink at the nearest restaurant to work on his night off. You don't really need him to show up in a tuxedo, of course. But if you're reading Amor Towles's jazz-era The Rules of Civility while drinking gin fizzes and Singapore slings, a man in black tie (or something) doesn't hurt.