Teenage movie, Plimsouls/Paul Johnson style music, disco
I remember only very foggy memory from movie from 90's. I saw it at least 20 years ago and I'm sure that is made in USA.
My foggy memory is American singer. He has short hair and he wears dark sunglasses. He is singer on the stage and he sings very good song. It's specific lyrics are "No! No! No! No! (twice). There were at least two verses and chorus. I remember that crowd of young teenagers dances in a music club. The song is very similar (at least chorus) to Paul Johnson - Get Get Down.
Other possible clues: it is very unpopular song (because I listened this track only once in my life) it sounds like "The Plimsouls" music band.