Yes, you could add a splash of the liquid from a jar of olives to your martini. Or you could pop open a bottle of olive juice formulated for cocktails by Gaea, a Greek food company that sells fine olive oils. The juices are made using brines left over from the company’s olive and oil production. Green olive juice is for use with gin. Brine from pimento-stuffed olives is designated for vodka, and it has a nice little kick: Gaea Dirty Martini Juice, $2.49 for 8.5 ounces, gaeaus.com.