"I don't know where all that came from," the Oscar-winner told reporters in Los Angeles recently. "Every co-star I ever work with I'm either having an affair with him, I'm about to get married to him, we're having a baby or we absolutely cannot stand each other. Because that's how you feel about everybody you know, right? You can't just get along and work with them. There has to be some sort of drama."
Witherspoon is divorced from her "Cruel Intentions" leading man, Ryan Phillippe, and is dating her "Rendition" co-star Jake Gyllenhaal.
"But, no, (Vaughn and I) got along great and we're very good friends and very much partners on this movie," she said. "We decided to produce it together and we re-wrote the script together and every day was like: 'How are we going to do this?' 'What are we going to do now?'"
Witherspoon said she learned a lot about being spontaneous on screen from collaborating with Vaughn.
"He's the funniest person I've ever worked with in my entire life," she said. "It was a challenge for me and I had to really keep up with him and he taught me a lot. He taught me a lot about improv and ad-libbing and I feel like I'm a better actor for that experience."
Celebrity Families of 2014 [PHOTOS]
Mindy Kaling mistaken for Malala Yousafzai