What was my sister thinking?

Once upon a time, my 19 year old sister was tasked with the job of babysitting 10 year old me. She dragged me along on a visit to her friend's new apartment.
The sat me in front of the tv and video player with the video of, yep,'Twinky'.
I was hooked until about 3/4 of the way through the film when I was dragged home.
I have been trying to remember the name of the film for years ever since. I knew it had something to do with a girls name, or nickname.
I never did remember the name of the actors in the film. The situation was a bit vague. I have been playing with keywords off and on for ages. Just cracked it. LOL.
Based on the premise of the film if they were trying to corrupt me, it worked.


I am looking for another film. No idea what it is about, but I do know how it ends.
A group of 100 or so teens or young people rush into a train tunnel. A train goes through at high speed. A group of adults, parents possibly, rush into the tunnel and they start pulling out bodies and laying them on the track, no blood as far as I can remember. It must have been the 60's or 70's when it was made and I would have watched it between 1974-1978. I was only a bub and completely shocked by what I saw. It put seame street in a whole new light.(there were no adults in the room).