You go out in your own car and eat, drink and be merry to your heart's content. Then, you call ScooterMan (or make arrangements earlier in the evening). ScooterMan shows up on a small scooter, which he folds up into the trunk (or "boot" if you're British) of your car and drives you home in your own car. Once you and your car are safely home, ScooterMan retrieves his scooter from your trunk and scoots himself off into the night.
Well, now that I think about it there are probably a dozen different liability angles you'd have to take care of, especially in the US. Unfortunately the scooterGirl pictured is not part of the service.