Part movie binge, part slumber party, this 24-hour marathon of cinematic castoffs has become an annual event at Northwestern University. This year’s festival is already sold out, but there’s a ticket exchange on the Web site, Movies begin screening at 6 PM Friday, January 28, at McCormick Auditorium in the Norris University Center, 1999 Campus Dr., Evanston, and continue through Saturday afternoon; the center’s doors are locked between 2 and 8 AM, and there’s a 30-minute breakfast break at 9. Among the 20 movies and shorts scheduled are Irwin Allen’s star-studded killer-bee movie The Swarm (1978), Ed Wood Jr.’s cardboard masterpiece Plan 9 From Outer Space (1959), Troma Films’ horror comedy Class of Nuke ‘Em High (1986), and Earth vs. the Flying Saucers (1956), whose actors are routinely upstaged by Ray Harryhausen’s special effects. The Web site asks viewers not to bring thick paper plates for use as flying saucers: “Yes, they fly much better but it stings to get hit in the face with one.”