Before you say anything, a perfect substitute for Vodka is apple cider vinegar, because we all know there are a thousand other uses for Smirnoff and most of them do not involve hair.
Vodka along with avocado and mayo is the perfect mix for shiny hair so if you decide to go for the alcohol, add 1 shot to a blender, half an avocado, one table spoon of mayo, two table spoons of honey and two tablespoons of coconut oil. Mix well and apply it to your hair.
After about thirty minutes, shampoo and condition as normal. Now as mentioned before ACV can be used in place of Vodka as both remove buildup and brighten the hair (its just not as fun).