Okay, so I had to tell DH about the plans. I was a little miffed at his reaction and lack of knowing what to do....I think he is afraid that she will get pissed and run away again...I say suck it up!
I told him that if it was our daughter (our now 8 year old) there would be no way in hell that she would go.
He sort of told her no....he asked her if there was something else they could do.
I told her she had no damn business being in a bar at 18!

She played the dumb card and said she had no idea it was a bar....blah blah blah....always miss innocent.

Come to also find out that the chatty girl that came to tell me about their plans was one of the chics who graduated last year, that my SD always tried to hang out with....the ones that went out drinking every weekend, got abortions, and had babies, etc....yeah those very same girls were the ones she planned on going with tonight. She just "happened" to run into her at school....cuz you know how often those really good kids go back and visit their teachers once they graduate....lol. Not sure if she is still going to do something with them....

My guess is that she called them up asap once she turned 18, thinking that her dad couldn't tell her what to do anymore etc. He even asked her when she though a good time to come home was......she gave him the ole "well I am 18 and I should be able to come home when I want". Not in my house! I told her to hell with that thinking and if she wanted to come and go as she pleased then she knows where the door is!

The good old "my house, my rules!"

So done with the bullSh**