The very best midnight movies are silly good fun and completely camp-tastic. When Cinecultist caught Wet Hot American Summer on its initial theatrical release two summers ago, it seemed like the kind of film best appreciated with a crowd, musical guests and prizes. Fortunately for fans of this The State-produced flick who appreciate seeing it in a theater with a gaggle of like-minded friends, the producers have brought it back for a run of midnight screenings at the AMC Empire 25 (234 W. 42nd St. between Broadway and Eighth Ave., $10) this weekend. Members of the cast will be there, including Janeane Garofalo, and at the last weekend of sold out screenings after Labor Day, viewers dressed up as characters ala Rocky Horror. Break out those terry cloth short shorts and head down there tonight.