Zach Galifianakis’ character, Ethan Tremblay, in the new comedy “Due Date” is sloppy, rude, backwards and lovable.

Too bad it’s impossible to love the movie.

Peter Highman (Robert Downey Jr.) is a high strung architect trying to make it back to Los Angeles for the birth of his child. Before his plane is ready to take off, he has an unfortunate run-in with Ethan.

They both get booted off the plane and Peter is put on a no-fly list. He has no choice but to drive across the country with Ethan.

The unlikely duo encounters all sorts of problems as they drive west, all exacerbated by Peter’s nearly-uncontrollable temper and the fact that Ethan might as well be a child.

Peter manages to start a fight with a paraplegic war veteran, aggravate the border patrol, punch a child and spit on a dog.

He’s completely and utterly unlikable, but his dark and furious antics are great for laughs.

Ethan is a horse of a different color and, unsurprisingly, is often the catalyst for Peter’s anger.

His antics include getting high while listening to Pink Floyd and driving, masturbating in the car and carrying his father’s ashes around in a coffee can.

If it doesn’t sound like the movie is an hour and 40 minutes of Galifianakis’ character from “The Hangover,” it should.

One difference between the two characters and their respective films is the hidden sincerity in Ethan.

There is about a minute and a half that makes me wish Galifianakis would do more “real” acting. Ethan’s father just died, and there are some wonderfully genuine moments of sweet sincerity from Galifianakis.

One of my favorite moments of the film involves Ethan, marijuana and Pink Floyd’s “Hey You.”

Ethan is jamming out to the song and smoking (with the windows rolled up) while Peter is sleeping. Peter eventually wakes up and is out of his mind.

This all sounds great, but is it worth the $9 movie ticket? No, and for a few good reasons.

First of all, if I want to watch “The Hangover,” I will watch it in the comfort of my own room.

It looks like Galifianakis is going to be stuck playing the same character in mainstream film.

Second, while dark and moody characters are a lot of fun, Downey’s character Peter is not. Characters like Downey’s Tony Stark from “Iron Man” have charisma to counteract their sleaziness, but Peter has none.

Watching the same temper tantrums over and over again is agonizing. Third, a lot of the gimmicks are pretty predictable.

Peter explains a dream he had to his wife at the beginning of the movie, in the biggest piece of obvious foreshadowing I have ever seen.

Bottom line, there needs to be a little bit more finesse in the comedy.

It’s great to see both of these actors getting more and more work, but what’s the point if the work is impossible to enjoy?

Save the money spent on the ticket for a better holiday season movie.