Witherspoon has been clashing with Vince Vaughn on set.

Reese Witherspoon is refusing to film a sex scene with Vince Vaughn. The pair have reportedly been clashing constantly on the set of romantic comedy 'Four Christmases' and now Reese is refusing to roll around naked sex scene with Vince. An on-set source told the New York Post newspaper: "Reese has an issue with the scripted sex scene. It is meant to be a funny, 'American Pie'-style
romp, full of bumps and laughs, but Reese is such a prude, she thinks it's just too much."