Blueberry?
Most people are aware of the fact that, when asked who he thought should play Iron Man in any film, Stan Lee immediately said Robert Downey Jr. He’s come to embody the role perfectly. He’s also just as irreverent as his character when on the set of the movies.
Downey Jr is known for hiding snacks all around the sets he’s working on, stashing them so that he can pull them out at a moment’s notice. In a scene from Avengers: The Age of Ultron that has been meme-d to death, Tony Stark offers Steve Rogers a blueberry in the middle of the conversation. This was not in the script, which explains why Steve looks confused.