Having trouble picturing Arnold Schwarzenegger as the world’s first pregnant man? Check out Universal’s trailer for Junior, which unveils our biggest action hero in the bloom of imminent motherhood. ”My nipples are very sensitive,” whines a suddenly vulnerable Arnold, who also can be seen swooning with morning sickness, suffering hot flashes, and modeling maternity menswear. Director Ivan Reitman says that between the gender-bending sight gags, you’ll find a ”realistic” romantic comedy. However, he says, the trailer barely taps the movie’s mother lode of laughs. ”Too many comedy trailers give away the best jokes,” says Reitman. ”I tried to protect all the best laughs in our film.” Which is as it should be: A trailer should always leave its audience expectant. Junior is due Nov. 23.