This is very easily done, it just takes some time.
Best done together with the other "Drinking" achievements
As soon as the bar is available on the wrecked boat, invite the girls for a drink. There are three posibilities per day, and after I think it was three days you would have to stock up again, which can only be done at the day.
You earn 4 coins for a perfect drink and 3 when it is good.
What I did was create a save and reload after the day was over. This way you don't add extra days to your survival just by pouring drinks, though you won't earn coins.