A film whose main purpose is to amuse and induce laughter, comedy deals with the preposterous and absurd aspects of human behavior with a sense of humor. The comedy is usually meant to make the viewer feel good, projecting the foibles of characters onto the screen for the audience to use as scapegoat for the ridiculousness of life. Always a hugely popular genre, there are many types of screen comedy: slapstick (the Mack Sennett shorts], screwball (The Lady Eve), conceptual (Schizopolis, The Meaning Of Life), satirical (The Seven Year Itch, Bob Roberts), the spoof (Airplane!), anarchic (Duck Soup), absurd (Anchorman: The Legend of Ron Burgundy), sex comedy (Porky's, American Pie), black comedy (Dr. Strangelove), the list goes on. Many comedy films written or starring comics with a sketch comedy background will use improvisation to produce humorous dialogue, as in This is Spinal Tap and The 40-Year-Old Virgin. While many comedy films are entirely light hearted (Ghostbusters, Animal House) comedy in films can also be an effective way of commenting on aspects of society, examining hypocrisies by showing how absurd they are. Dr. Strangelove, for example, makes fun of the arms race and the Cold War by exposing how world leaders act like bullies in a playground sandbox. Some types of comedy, such as the black comedy, seek to deal with the painful aspects of life in such a way that the humor not readily apparent in such things as Nazism or racism is used to diffuse the horror surrounding it. Even if a comedy is meant to disturb (such as the media satire Man Bites Dog), its primary goal, regardless of happy ending or likable characters, is to look at all things with a sense of humor.