Kevin Hart giveth and Kevin Hart taketh away in “Night School.”

He never seems more generous than when he’s stepping back, taking on the Ice Cube role in “Ride Along,” reacting and playing the straight man for Tiffany Haddish and especially Romany Malco.

And he never seems smaller than when the star and producer insists this interminable, only occasionally tolerable farce about “second chances” goes on and on past its climax to give his character a gratuitous prologue and epilogue to complete his “character arc.”

It isn’t necessary. And it doesn’t help.

Hart mugs and riffs and tries to wring a giggle out of the five-handed script that still needed work. Scenes go on past their payoff, gags are flogged to death after the punch line. Haddish hurts herself attempting to share the heavy lifting. When you’re repeating your catch phrase from “Girls Trip,” you know girlfriend has run through her repertoire.

“Booty hole!”

Teddy Walters (Hart) ends up in “Night School” because he didn’t finish high school. His no-nonsense dad (Keith David, hilariously profane) knew he was in trouble before Teddy blew the proficiency test required for graduation.

“I’m gonna succeed in the SCHOOL OF LIFE!” Teddy declares, storming out.

And he does. Selling is his calling, and he’s cock of the walk at Atlanta’s Joe’s BBQ City. He’s willing to be called “My own little Gary Coleman” if it means the owner leaves the running of the business to him when he retires.

He’s driving a Porsche and dating WAY out of his league and height (Megalyn Echikunwoke). Then he screws it all up.

He can join his high school buddy (Ben Schwartz) in financial planning (stock and annuities) if he can just swing a GED. He’ll just sweet-talk/sell himself to the principal at his old high school…

No dice. The “smart kid” he hated (Taran Killam) is now principal, and he’s “a principal with principles!” And that mouthy woman he bickered with in traffic, the one who called him “a burnt leprechaun?” She’s Carrie (Haddish), the night school teacher.

“No short cuts!”

Thus is Teddy with his collection of learning disorders thrust into a class with a Mexican waiter he got fired (Al Madrigal, flirting with stereotyping), a Molly-moving punk (Anne Winters), a dimwitted mover (Rob Riggles), an inmate in prison (Jacob Batalon) taking the class via Skype, a downtrodden but “blessed” housewife (Mary Lynn Rajskub) and a bottling plant layoff who came to realize “The Terminator” wasn’t just a movie, “it was PROPHECY!”

Jalen (Malco, of “Weeds” and “The 40 Year Old Virgin”) declares “the revolution will NOT be roboticized!” And every damn line out of his mouth is funny. Malco all but steals the picture, giving advice — “If you’re lying WITH her don’t lie TO her” — making even the lamest running gag catch-phrase funny.

“THAT’s what’s up.”

Romany Malco crushes it.

The best efforts of the rest of the cast don’t add up to more than a random good joke here — teacher telling Ms. “Blessed,” “Aww, look at you, all cute and makin’ America ‘Great Again.'” — and Hart sight gags. Teddy has to wear a chicken costume “marketing” a Christian Fried Chicken joint’s menu to passing traffic — “It’s chicken from THE LORD!”

It’s probably not worth going after this movie for Teacher Haddish’s solution to Teddy’s dyslexia and dyscalculia (inability to comprehend math). She takes him into the MMA hexagon at a local gym, quizzes him and screams “FOCUS” as she pummels him every time he gives the wrong answer.

I don’t think that medical or school board approved.

But Haddish’s profane high school teacher who butchers the Queen’s English is something of a stretch from the start. It’s a make-or-break autumn for her, with three movies coming out. Maybe that’s why she’s run out of fresh material already. I kept seeing the late LaWanda Page of “Sanford & Son,” in her increasingly broad, desperately lowbrow shtick this time out.

It’s Hart’s party, though, and even if the strain and effort shows, he works up a sweat to give the people what we want – making face and overreaching for much of “Night School’s” nearly-two hours.

But the funniest single moment might be a busted take. The Christian Chicken crew is holding hands for their AM prayer, and Teddy twitches and twists and kvetches about how tightly the little old lady cook is holding his. Look at the extra playing the cook. She’s fighting a losing battle with cracking up.

If only we could share her joy.

MPAA Rating:PG – 13 for crude and sexual content throughout, language, some drug references and violence

Cast: Kevin Hart, Tiffany Haddish, Keith David, Taran Killum, Anne Winters, Romany Malco, Rob Riggles

Credits:Directed by Malcolm D. Lee, script by Kevin Hart, Harry Ratchford, Joey Wells, Nicholas Stoller, John Hamburg . A Universal release.

Running time: 1:51