In 1806 a New York newspaper editor named Harry Croswell gave us the first definition of the word cocktail: "a stimulating liquor, composed of spirits of any kind, sugar, water, and bitters ..."
So what's a 3/4 Cocktail? It's my way of describing a spirit free cocktail. You still have the sugar, water, and bitters. As long you have at least those three ingredients, the possibilities are infinite. Bitters are highly concentrated alcoholic tinctures, so a 3/4 Cocktail isn't completely booze free, but it's quite close.
In recent years cocktail programs have made a point of emphasizing low or no alcohol drinks, or at least not relegating them to the proverbial kids table in the room of cocktails. People have different reasons for wanting a refreshing and delicious libation without alcohol. In my case, I'm standing in solidarity with Ms. Cocktail Den, whose temporary medical issue renders her unable to drink booze for a short period of time.
There's no real formula for creating a 3/4 Cocktail. Personally I like to mix fresh citrus juice, a sweetener, a couple dashes of bitters, and ice (this is the water), shake it up so I follow the Hamlet Cocktail Conundrum, and strain into a chilled glass. I suggest adding flavored seltzer water to increase the drink's volume and intrigue factor. For example, the pictured 3/4 Cocktail is a No Booze Boricua, a spin on the Pina Colada. Combine juice from 1/2 a lime, 1.5 ounces fresh pineapple juice, 1 ounce cream of coconut, .5 ounces super simple syrup, 2 dashes of Liquid Gold bitters from Embitterment, shake with ice, and top with orange seltzer water.
If I was one of the guys on The Big Bang Theory I'd write a complicated formula explaining how a 3/4 Cocktail can get you 100% satisfaction. I'm not one of those guys. I'm not crazy (my mother had me tested), so trust me on this one. Cheers!