The celebrity rumor mill is on overdrive, as it appears Reese Witherspoon and Vince Vaughn are not getting along on the set of their new film, “Four Christmases.” Apparently they have completely opposite personalities, which no one considered when casting the two as romantic comedy leads. I don’t really consider that a newsflash. Did the casting director even look at these two people? Reese looks like she just came from a magazine cover shoot by 8 a.m. every morning, whereas bloated Vince Vaughn normally looks like you could squeeze the grease from his head.

Spies working on Reese Witherspoon and Vince Vaughn’s new film, “Four Christmases,” say the tension between the stars is even more entertaining than the script of the romantic comedy. Famously alpha personality Reese — who named her production company Type A Films — is clashing with Vaughn’s laid-back approach to work.

“Vince rolls onto set in the morning looking like he just came in from a night out, while Reese will arrive early looking camera-ready,” says our San Francisco source. “Then Reese tries to force Vince into blocking out each scene and running through their lines as Vince tries to convince her that he’s an ad-libber and wants to play around and see where the scene goes.”

However, the movie, about a married couple who spend a Christmas with each of their four divorced parents, remains on schedule and on budget. “She’s a one-take perfectionist and Vince likes to try it a few different ways,” snickers our snitch. “Sometimes Vince will be standing behind her and he has this look on his face that he just wants to kill her!”

[From Gatecrasher]

To me, all the things that were just outlined as Reese’s “faults” are simply being professional. Unless a director says otherwise, I’m under the impression that actors are generally supposed to know their lines, and rehearsing them is probably a good idea. It’s lovely for Vince Vaughn to want to roll out of bed and improvise, but other people have things to do with their day too. It’s not fair to expect someone else to do take after take because that’s fun for you. Unless that’s what the director’s asking for, of course. But Vince Vaughn just sounds lazy to me. There’s just something about the way he speaks and the way he presents himself that says, “I don’t give a rat’s ass about anything. Personal hygiene? Boring. Being a professional at work? Not fun. Putting on a shirt without six holes in it? Sooo last year.” That was my best early-Monday-morning-Vince-Vaughn impression. It could use some work. Either way, I know we’re supposed to hear this gossip and think Reese is an uptight bitch, but I tend to think the problem is more the lazy slob.