Starring: Seth Rogen, Katherine Heigl, Paul Rudd, Leslie Mann, Jay Baruchel, Jonah Hill, Charlyne Yi, Jason Segel, and Martin Starr

It's hard to believe that it's been five and a half years since Knocked Up hit theaters.  It's the quintessential pregnancy movie and one damn funny comedy.  It's also one of the few good movies starring Katherine Heigl.  It's even harder to believe that Judd Appatow has decided to release a spinoff sequel, the upcoming comedy This Is 40.  Before we check out this new flick at the box office, let's revisit its hilarious predecessor.

Ben Stone (Seth Rogen) has yet to grow up.  For the last decade or so, he has been living off a settlement received from the Canadian government for a car accident years ago.  With $900 to his name, he now lives with his friends Jason (Jason Segel), Jonah (Jonah Hill), Jay (Jay Baruchel), and Martin (Martin Starr).  They get high all day every day.  Their only prospect for income is a website their launching called Flesh of the Stars.  This site is akin to Mr. Skin and will probably not lead to a very lucrative future.  It's needless to say that Ben is not living the dream.

Alison Scott (Katherine Heigl) is just the opposite.  Living with her sister Debbie (Leslie Mann), her brother-in-law Pete (Paul Rudd), and their two daughters (Iris and Maude Apatow), she's a goal-oriented woman focused on building a career at E!, the television channel.  Because of her strong work as a producer off the air, her supervisors (Alan Tudyk and Kristen Wiig) decide to promote her and put her on the air.  She goes out to the club to celebrate later that night and meets Ben.  They hit it off, go home, and get busy.  Because of a miscommunication, Ben neglects to wear a condom.  Eight weeks later, Alison is pregnant, and the long, hard road of parenthood begins for both of them.

Knocked Up is certainly a film that gets pretty wild and raunchy, but it's also a film that broaches several substantive real life issues about pregnancy, parenthood, and adulthood.  It’s definitely a movie with a lot of heart.  Director Judd Apatow spends the movie building stereotypes around his main characters and then contradicting them.  He spends the movie making Rogen's Ben look like the last guy in the world who should be a dad.  He spends just as much time making Heigl's Alison look like a woman more interested in accelerating her career at E! and maintaining her social standing than bringing her unborn child into the world with a functional family. Making these stereotypes unapologetically clear leads to most of the laughs in the film.  He then contradicts them, and that's where Knocked Up gets its heart.

Our leads Seth Rogen and Katherine Heigl bring quite a bit to the film.  Individually, Rogen does some of the best comedic work of his career.  He hilariously plays Ben up as this stoned loser with often comical insights.  While not necessarily that funny, Heigl plays the straight character that facilitates all the funny situations around her character.  She gives us a relatable character in a tough situation.  Together, Rogen and Heigl have some great chemistry on screen.  Between Rogen and "the pregnancy hormones", there's quite a bit of comedy.

Paul Rudd and Leslie Mann also bring a great deal to the film.  Together, they comically bicker like an old couple about the most mundane things.  They certainly keep the chuckles flowing when they're on screen together.  Beyond their chemistry as a couple, Rudd and Mann have good chemistry with Rogen and Heigl respectively.  Whether driving down the road listening to Britney Spears or having a little fun at Cirque du Soleil, Rudd and Rogen share an incredibly hilarious bromance on screen.  Similarly, Mann and Heigl have great comedic chemistry as siblings, particularly because Mann is in denial that she's aging (a precursor to This Is 40).

The real comedic joy from Knocked Up comes from the flurry of comedic stars making appearances in cameos and bit roles.  Ben's friends — Jason Segel, Jonah Hill, Jay Baruchel, and Martin Starr — are all about getting high and getting wild.  Segel in particular delivers quite a few laughs.  Kristen Wiig and Craig Robinson have minor roles in the film as well.  Wiig has very few lines, but she manages to nearly steal the show with some biting wise cracks.  As a bouncer who tells it like it is, Robinson might just be my favorite part of the movie.  Beyond this plethora of comedians, there's a slate of hilarious cameos from celebrities like Ryan Seacrest and James Franco.