Why this film doesn't work

Umm...it's very believable that she would spend the night with him. In the movie, they reference that both characters are in their early 20's, I think they say around 23 or so. Rogen's character was obviously no stranger to partying and intoxication. Heigl's character works for the entertainment industry and, from personal experience, those jobs allow for very minimal, if any, social life. So it's safe to say that someone in her shoes probably hasn't been out partying, or even with a man, in quite some time.

He buys her a few beers to initiate conversation, yes. But if you actually watched the movie, you would know that she didn't decide to take him home immediately following. They show them getting progressively more intoxicated throughout the night. You can notice they are stumbling out of the bar before going back to her place. They're both drunk, and neither of them have slept with someone in probably a decently long time. You'd be amazed at some of the one night stands that occur when people are drunk and sexually frustrated. There are thousands of people, myself included, that have woken up after a serious bender next to someone that makes us question just what we were thinking the night before. That's very realistic.

Now, you could argue that the ambiguously happy ending, the one where they love eachother and ride off into the sunset together with their new baby, is farfetched. I'd agree with you on that one. But as far as the one night stand goes, that part was proabably the most realistic, because it happens all the time. Maybe you just don't go out very often or you're never interested in one night stands. To each his own. But to say that a scenario like this would "never happen", just makes you pretty ignorant to what is actually happening around you every day.

I buy that she would get drunk and *beep* him... but I also agree that the two leads have zero chemistry...

I do what I say and I say what I mean

Women don't get it because they refuse to admit that they've fallen for a loser or two in their life. In the audio commentary, Apatow even says the point is that Rogen was supposed to start off as unlikable and not a good partner to Heigl but he had to grow up and become the man that Heigl's character needed to be which he did at the end. And the chemistry part was Heigl's fault not Rogen. She hates being associated with the film because she felt that the movie was sexist which is hilarious considering all the female dominated rom coms that feature three dimensional women with their one dimensional male counterpart. At least Knocked Up shows us that both men and women are flawed and shows that not everything is a happy ending, horse carriage, riding off into the sunset. As a guy, as someone who had an unexpected pregnancy in his early 20s and as someone who's been in his share of relationships, this is one of the most realistic rom coms I've ever seen.

Girls don't understand why Heigl was with Rogen because they don't find him attractive. They can say whatever they want, that's the reason.

Although I still loved this movie and thought it to be extremely funny and sweet (you really do have to suspend your disbelief) I agree that it is extremely improbable. In my lifetime I've seen tons of very attractive women date/marry or go out with men who are not nearly as attractive as they are they always had something else going on. Most likely a good job/money. I'm not saying this is right. I'm saying it's the way it is.

Yeah, Ben was funny and charming in that slacker way but he had no job, no money, was a major pothead, lived with a bunch of potheads who were his buddies, was uneducated, lacked ambition, resources...She on the other hand apart from being very pretty had a good job and was moving up and took her life seriously. While the one night stand that ended up in pregnancy is believable the fact that she'd want to have the baby and stick it out with him to see if it will work makes no sense.

ugh, enough with this "out of her league' and "out of his league' horse crap, try evolving

++++++
Love means never having to say you're ugly. - The Abominable Dr. Phibes

Funny for a movie that "doesn't work" it did awesome at the box office. I think the studio and producers would disagree entirely.

I thought this movie was hilarious and found the relationship between the Rogen and Heigl characters seemed realistic.

"Gorgeous" women require at least ONE of these:
1) Money
2) Great looks
3) Big schlong

Everything else is just icing on the cake.

I disagree completely. When they meet in the club she thinks he's nice for getting her the beers and then when he goes over and chats to her she thinks he's fun and funny and she gets along well with him. At this point she's also drinking so whether or not she finds him physically attractive isn't a factor here, she thinks he's a nice, sweet guy and she's happy and drunk so decides to sleep with him. That is very realistic. She regrets it the next day and has no more interest in him, still realistic. She only contacts him again when she finds out she's pregnant (which is a good thing of her to do) and once they meet up she still isn't impressed with him. However, over the course of her pregnancy they hang out more and more and she remembers/rediscovers that she finds him funny and sweet and caring and she gets attracted to him because of those reasons. Still realistic. Ben started off as a slacker and a stoner and that was what ended up causing her to end things with him because she didn't want to change him and she wanted him to be happy. He ended up growing and changing anyway and he came forward. After that there is no reason why she wouldn't be with a man who got a job, got a new apartment, was prepared to share the responsibility of the baby with her and who she liked.

So, as a woman, I would say it does work and I definitely find it believable. I'd take Seth Rogan over a boring, pretty boy any day of the week.