Put some crushed (or cubed) ice into a shaker. Add the vermouth and swirl it around in the ice so it coats the shaker and chills in the ice. Add the gin and the olive brine. Shake to blend. Strain the drink into 2 chilled martini glasses. Place 3 olives in each drink. I personally prefer them to be skewered on a pick but I suppose it’s not entirely necessary. Serve immediately.