It may not carry the same fear-inducing firepower as challenging foods like tripe, brains, or other "variety meats," but there's an ingredient in occasional use behind the bar that sometimes rattles the unsuspecting customer: raw eggs.
Mixing eggs with liquor has a long heritage. A prime mover at colonial taverns was the flip, a drink typically made with a spirit such as rum, cream, and raw eggs (other ingredients such as hot beer or sherry were not uncommon); and while it's now thought of primarily as a holiday tipple, eggnog was once a fairly common concoction to call for across the bar. Egg whites became a staple ingredient in drinks such as the gin fizz and the whiskey sour, adding foam and body to the drink while slipping a little sustenance to the imbiber. And for sheer decadence there was the Knickerbein, composed of several liqueurs in a glass topped by the unbroken egg yolk and a mound of whipped egg white; the drinker was instructed to first inhale the froth, then drink the liquor while leaving the yolk untouched, and finally to gulp the remaining spirits while breaking the yolk in the mouth.
Changing tastes combined with salmonella scares helped drive raw eggs almost completely from the bar. But, as with the resurrection of offal at fine dining establishments, creative bartenders are rediscovering the benefits of raw eggs. Perhaps the best example of this is the ascendance of the Pisco Sour, a cocktail made with the South American brandy called pisco, sugar and fresh lemon juice; the drink is typically shaken hard with raw egg white to produce a foamy head, upon which is then dribbled a few drops of bitters. By dashing the bitters atop this stage of foam, instead of mixing it into the cocktail, the drinker is greeted by a complex aroma when taking a sip, and the drink takes on an additional dimension.
While raw eggs lack the gastronomic gravitas of foods such as Rocky Mountain oysters, they still inspire a few squeamish looks in a bar. What's your take? Do you hanker to have a whole egg served to you in a cocktail glass as part of a brandy flip, or do you think the closest your booze should be to your breakfast is when the waiter places your Bloody Mary next to your eggs Benedict?