The film that made everyone feel like a genius, Dumb And Dumber is 20 years old, and it's still as daft as ever. Check out the Farrelly Brothers' first (and possibly greatest) movie in the open air, and try not to laugh at the getting-off-the-moped scene. Go on. It's impossible. Warning: do not try any of this at home, or outside, or anywhere else. Please arrive on time as latecomers may not be admitted.