In a pinch, a juice box can serve as a nice mixer with vodka.
We had a full container of grapefruit juice in the fridge (rare) and I was in the mood for an "adult beverage" (not so rare). Unfortunately, grapefruit juice was too not right. And we had no cranberry juice. All we had were some random juice boxes left over from a reunion BBQ. Fortunately, a grapefruit and juice box cocktail was just perfect!