Girls Just Want to Have Fun (1985)

http://www.imdb.com/title/tt0089208/

fun 80s movie with a 19 year old Sarah Jessica Parker, a 20 year old Helen Hunt, a 13 year old Shannen Doherty and if you watch it carefully, you will see cameo appearances by 19 year old Robert Downey Jr. (who was dating Sarah at the time in real life) and 22 year old Gina Gershon