LORELAI: Hey. I am not even going to begin to tell you how completely insane it is to take off with anyone you don’t know, or drink things that you don’t know what’s in them, or act like you have a clue when you don’t, but so help me God if you ever pull a stunt like this again, it will not be around my kid! Do you understand me?
Any illusions Madeline and Louise might have had that Lorelai was a “cool mom” who would buy them booze and let them mess around with older guys they just met is instantly dispelled in this scene. Lorelai is not naive about what young men might do in this situation, and basically tells them that they could have been date raped if she hadn’t come after them.
Most of all, Lorelai cannot tolerate Rory hanging out with girls who might lead her astray or get her into danger, so we know that Rory’s friendship potential with Madeline and Louise is now greatly reduced. It becomes obvious in this episode that Paris is Rory’s destined best school friend, as she isn’t boy-crazy, enjoyed staying at the concert with Rory, and clearly respects Lorelai.