AceShowbiz -

Robert Downey Jr. just learned that Gwyneth Paltrow didn't like someone calling her snob. At a press conference for "Iron Man 3" in London last weekend, Paltrow gave Downey a slap on his face when he called her so.

At the press conference, Paltrow told the audience that she was "really surprised" that the action film she stars in with Downey was loved by everyone including herself. Downey then poked fun at the actress who was recently named the most-hated celebrity in Hollywood by Star magazine.

"Shocked?" Downey, who played Tony Stark in the film, didn't let Paltrow finish her words. He added, "You're such a snob." Trying not to laugh so hard, Paltrow couldn't say anything for a moment while everyone laughed at that joke. Downey leaned forward to kiss her cheek as an apology, but she gave him a light slap on his face instead.

It wasn't the first time Downey made fun of Paltrow when they were promoting "Iron Man 3". Last week, during similar press conference in Paris, Paltrow made Downey speechless when she spoke French fluently. Downey mocked his co-star, saying, "I would have spoken French but I was raised by wolves. They don't teach French in jail!"