Transformers: Revenge of the Fallen” is a horrible experience of unbearable length, briefly punctuated by three or four amusing moments. One of these involves a dog-like robot humping the leg of the heroine. Such are the meager joys. If you want to save yourself the ticket price, go into the kitchen, cue up a male choir singing the music of hell, and get a kid to start banging pots and pans together. Then close your eyes and use your imagination.