Egads! Could it be that actors with dissimilar personalities and performance styles are experiencing some professional friction even as they pretend to love each other in front of a movie camera? Gape in disbelief at a report that the set of Reese Witherspoon/Vince Vaughn holiday romantic comedy Four Christmases is rocked by not-getting-along-great scandal that could threaten the civility of their small talk around the craft services table! "'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.' ... '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!'" [Gatecrasher]