"One for the road" is one last thing you do before leaving some place. Example: "Come on, let's play one more game of pool for the road." This saying often expresses having one last drink. Example: "Bartender, I'll have one more drink for the road." Note: "The road" does not necessarily mean that you will drive a car; it just means that you are going to leave the place soon. Example: "Are you sure you won't have one for the road?" Answer: "Sorry, I can't. If I leave now I will just make it on time." To have "one for the road" is to have one more and stay just a little bit longer.