Robert DeNiro loves comedy. Who knew?

After decades as America’s most respected dramatic actor, DeNiro discovered that he enjoyed making people laugh in “Analyze This,” where he tweaked his most famous roles to create mob boss Paul Vitti, who was in therapy with psychiatrist Ben Sobel (Billy Crystal). In a typical therapy session, Sobel would suggest that Vitti was not used to hearing the word “no,” and Vitti would respond that he often heard people say, “No! Don’t kill me!”

In the sequel, “Analyze That,” Vitti pretends to be crazy in order to get out of jail (it is worth the price of admission to see him stand on a prison dining table belting out a ballad from “West Side Story”), and he is released into the custody of Dr. Sobel. After some unfortunate attempts at a job that does not involve any felonies, he ends up as an expert advisor to a “Sopranos”-like television show. Meanwhile, he has to figure out how to survive a war between two rival mob families.

There are some slow patches, and Lisa Kudrow as Sobel’s wife is badly misused. The plot doesn’t go anywhere and the attempt to make the pretentious producer of the television show funny does not work at all. But it is sheer joy to see DeNiro give everything he’s got (which is plenty) to the pure pleasure of comic madness, and every time he comes on screen, the movie takes off like a rocket. There is also a special pleasure for fans of “Raging Bull” in seeing DeNiro onscreen with the woman who played Vicki LaMotta, Cathy Moriarty. They still have great chemistry. It is fun to see the talented Anthony LaPaglia, who usually plays Italian-Americans in movies like “Frank Nitti” and “The Client,” using his original Australian accent. And be sure to stay for the outtakes at the end. I know they have become a cliché, but these are worth the wait.

Parents should know that the movie has very strong language (lots of f-words) and a lot of violence. It may be comic, but it is bloody and in some cases fatal. There are also sexual references and situations, including adultery, some graphic.

Families who see this movie should talk about what determines whether people can change. And they should discuss the way that both Vitti and Sobel are still so tied up in (and by) what their fathers thought of them. If you were going to write a third movie about these characters, what would you have them do?

Families who enjoy this movie will also enjoy “Analyze This” and “Married to the Mob.”