As it is, Greg is Jack’s son-in-law. They appear to get along, but one of those comedy misunderstandings occurs and soon they are mistrusting each other again. Spoiler alert: They work it out by the movie’s conclusion.

So you get rid of all the other characters and have these two guys move into an apartment together. Or maybe they go on a road trip. They get on each other’s nerves. Hilarity ensues. You might even be able to make it into a TV comedy series: “Greg, you got some ’splainin’ to do!” In this episode, a cute-as-a-button sales rep for a drug company (Jessica Alba, “Machete”) recruits Greg, a nurse, to promote an erectile dysfunction pill. Many hilarious boners ensue (at just about that level of humor).

It took two studios to pay the salaries demanded from Stiller and De Niro, Dustin Hoffman and Barbra Streisand (both wasted), Alba, Owen Wilson, Blythe Danner, Teri Polo, Laura Dern and, yes, that was Harvey Keitel seen fleetingly in the trailer. The picture may actually earn back its production cost.

Directed non-memorably by Paul Weitz, who had nothing better to do after the crash landings of “American Dreamz” and “Cirque du Freak: The Vampire’s Assistant,” “Little Fockers” is proof that some film series go out with a whimper and can’t muster a bang. Even after taking boner pills.