Close your eyes, click your heels together three times, and think to yourself, "There's no day like 4/20." To finish your herbal holiday off right, Bacchanal will host its annual movie screening tonight: "The Dark Side of Oz." As the title suggests, the trippy, music video-like film combines music from Pink Floyd's The Dark Side of the Moon with visual scenes from "The Wizard of Oz." Tonight's weather forecast predicts a storm, so the screening will be held in Lerner Cinema instead of on Low Steps.