Society (1989)
http://www.imdb.com/title/tt0098354/

Genre: Comedy, Horror, Mystery
Cast: Billy Warlock, Connie Danese, Ben Slack
Director: Brian Yuzna
Writers: Rick Fry, Woody Keith

Plot: Bill is worried that he is ‘different’ to his sister and parents. They mix with other ‘upper class’ people while Bill is more down to earth…

source