This is an easy achievement to miss if you're not careful. It will unlock at the end of the 5th Day if you stay in the Stray Sheep after everyone else has left, and do not leave early. To pass the time, speak to everyone at the bar twice then take a seat at the booth with Vincent's friends. Now speak with each of your friends until they decide to leave. There will be an option for you to stay or leave with them, select "Be careful.." and this will unlock. This can be done on other days too such the 8th Day.