Tina Fey and Amy Poehler reunite for “Sisters,” a slim excuse for a comedy in which two grown siblings say goodbye to their childhood home by throwing one last party there. The movie checks every item on its to-do list: jokes about middle age, references to the 1980s, crude humor, a romantic subplot. What the movie forgot was a script worthy of its two stars.

Fey and Poehler play the Ellis girls, whose personalities are difficult to define and don’t quite suit the actresses. Kate (Fey), a single beautician, is a lifelong party girl with a well-adjusted teenage daughter (Madison Davenport). Maura (Poehler), a divorced nurse, is a compulsive do-gooder with a condescending streak: She assumes all Korean manicurists are slaves and thinks anyone disheveled is homeless. Both women are hit hard by the news that their parents (James Brolin and Dianne Wiest) are selling their childhood home in Orlando (actually a house in Dix Hills, one of the film’s more convincing performances).

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The now-empty home becomes the perfect place for the Ellis sisters to throw a middle-age rager with all their high-school friends, even irritating ones like movie-quoting Alex (Bobby Moynihan) and sad-sack Kelly (Rachel Dratch). Thanks to a well-stocked drug dealer (John Cena), several aforementioned Koreans (led by a rather good Greta Lee) and a troupe of lesbian DJs (one of the film’s less successful jokes), the party spins out of control. Maura’s obligatory love interest (Ike Barinholtz) and Kate’s archenemy (Maya Rudolph) flicker in and out of frame.

Story8 LI locales where Fey, Poehler shot ‘Sisters’PhotosTina Fey, Amy Poehler film 'Sisters' in HuntingtonPhotos55 movies shot on Long Island

The film’s screenwriter is Paula Pell (a veteran of “Saturday Night Live”), but “Sisters” feels largely improvised. Fey and Poehler are good at that — both are alums of Chicago’s Second City improv troupe — but here they grab so quickly for jokes that they forget their characters. Poehler’s goody-goody can have quite a potty mouth, while Fey’s hot mess can suddenly turn icy. Maybe the actresses are subconsciously reverting to type; they were much better cast as the sassy-meets-classy duo in “Baby Mama” (2008).

Directed by Jason Moore (“Pitch Perfect”), “Sisters” deserves credit for wresting the crazy-party genre away from the boys. Still, Fey and Poehler deserve better, and are capable of so much more.