Kascha and Friends (1988)

Kascha's two girls friends, Samantha Strong and Charlie Waters are old high school rivals. When Charlie invites Samantha to her birthday party the rivalry starts again. Samantha is convinced that Charlie remembers their birthdays are on the same day and is having the party to upstage Samantha. To out flank Charlie, Samantha and her boyfriend Peter North call calls all their joint friends to promise and deliver delicious erotic favors if they come to Sam's party! Why don't you come to Sam's party too?