Coarsely grind the coffee beans.
Add the coffee to the mason jar and pour in the vodka.
Screw a lid on tightly and give the jar a good shake.
Let it sit for a couple of days, and shake it occasionally.
Once the liquid turns a nice, rich, dark-brown color, strain it through a coffee filter and discard the grounds.
Store the coffee-flavored vodka in a clean jar with a tight-fitting lid.