Reese Witherspoon is a tiny little peanut, while Vince Vaughn is a big guy, even by Hollywood standards.  Their height differences created some challenges while filming Four Christmases, since Reese's character wasn't intended to be so much shorter then Vince's.

"He's 6'5" and I'm 5'2". We had a really funny scene, I
don't know if it's in the film any more, where he rolls over onto me.
We were in bed and then at the very end he rolls over and goes to sleep,
but he rolls over and lays on top of me. It was like a tree trunk had
just landed on me. I kept going, 'Tim-berrrrr!' It was really funny.  I stood on a lot of boxes and they had to build ramps that were about
the same size as where I should be. It was a challenge, especially the
kissing scenes. It was hard to get up there to kiss him but we worked
it out."

And the dancing scenes were even harder. Vince just had to carry Reese!

"And he had to pick me up for half the dancing. He's actually holding
me in the air so we can stay in the same frame. He's a fantastic
dancer. A very, very good dancer, which you'd probably figure from
Swingers. They were teaching us dance moves. I just couldn't keep up
and he was like, 'Oh, it's a one-two cha cha cha'."

I can't WAIT to see this movie.  Who else is excited?!?