The Salty Dog is, in truth, nothing more than a Greyhound with salt around the rim (step off, margaritas, you don’t own that). Combine one and a half ounces of vodka and two parts grapefruit juice into a shaker with ice, shake well and strain into a chilled highball glass with salt around the rim. To get a little more of an effervescent kick, top off with some Fresca.