Who is Arnold Schwarzenegger's latest casualty? Judging from this photo, it's the rabbit. In Junior, Arnold reteams with Twins costar Danny DeVito to play, of all things, a pregnant man. But the prosthetic pregnancy didn't garner sympathy for the father of three among students at San Francisco's Synergy School. Worried about kids straying into a shot, the production kept youngsters from leaving the grounds until Arnold finished a scene. ''I had to stay until six,'' groused one 7-year-old. Was it worth the wait? ''DeVito was cool,'' says the student. ''But Arnold was wearing [hair] gel.''