Director Jacques Demy's propensity for making a workable comedy out of the least likely material is once more put to the test in A Slightly Pregnant Man. Marcello Mastrioanni plays the title character, and, yes, he's in "the family way." The film plays the role-reversal gag to the hilt -- sometimes to excess. But Mastrioanni always manages to make his character's plight believable, which is more than can be said for Billy Crystal in Rabbit Test or Arnold Schwarzenegger in Junior. A word of caution: though the title may seem frothy and frivolous, A Slightly Pregnant Man may prove unsuitable fare for children. The film's original French title--which must have sorely tested the patience of theatre managers with small marquees--was L'Evenement le plus important depuis que l'homme a march sur la lune.