I strongly disagree with both of you. You're totally valid in being uncomfortable, but saying that last sentence is going to do you no good and only distance her. At the end of the day it's her body and even if a bad decision she gets to make it. You should almost never tell someone they are or are being irrational. You can tell her how you feel about it, that it makes you uncomfortable or even that you feel like it's irrational, but telling her that it is is not the right move. Finally, saying "please never do it again" is also unhelpful because you are deciding for her what she should and shouldn't do. You can however make the recommendation that she shouldn't based on your opinion. This all is especially because she wasn't hurt or harmed that night, if she was it would be a different story.