I need a name of a movie I think the year is about 80's or 90's I think it was on USA late night. There is only one part of the movie that I remember 2 girls went to a party and went up to the bar and ask for a coke. (pop) But instead got coke (Drugs). That is only part of the movie I remember.

Got it finally! I remembered that scene. It's this one;

Welcome to 18 (1986) (http://www.imdb.com/title/tt0092199/)
Welcome to 18 Movie - The 80s Movies Rewind (http://www.fast-rewind.com/welcometo18.htm)