For the people who do not know what Saturday the 14th is here is a summary of the movie from IMDb
http://www.imdb.com/title/tt0083033/ "Primarily a spoof of the Friday the 13th series, but also takes shots at several other horror films. After his family moves to a new house, a young boy discovers a mysterious book describing the curse hanging over the date of Saturday the 14th. Opening the book releases a band of monsters into the house, and the family must join together to save themselves and their neighborhood"