One does not simply walk out of a Marvel Studios movie before the credits are over. As this has been the routine since 2008, everyone should know this by now, especially since we’re now officially into Phase Two after ‘Iron Man 3’ opened a little over a week ago. And speaking of the Armored Avenger’s third solo feature film, did you stick around to see what surprises were in store after the credits rolled?

If the answer was no, then I have two things to say to you: 1) Why not?! 2) You should not read any further because there are massive SPOILERS ahead. If you have any plans of seeing ‘Iron Man 3’ in theaters any time soon and don’t want to have this surprise ruined for you, then stop reading right now. I mean, I can only stall for so long, folks!

If you weren’t one of the people who contributed to Shane Black’s $174.1 million opening weekend (and $72.5 million second weekend), then you missed out on seeing the Science Bros. reunite in one of Marvel’s signature post-credits scenes. That’s right! Robert Downey Jr. and Mark Ruffalo, his costar from ‘The Avengers’, shared the screen for a playful scene after ‘Iron Man 3’ as Tony Stark and Bruce Banner in a sort of “therapy session”.

Previously, Ruffalo stated that his Hulk would not be seen until ‘The Avengers 2’, but he never said anything about Banner staying out of the spotlight. Recently, while promoting his new film ‘Now You See Me’, he spoke to I Am Rogue about his surprise appearance and how it came to be:

“It was literally, they were about to wrap the movie and I saw Robert [Downey Jr.] at the Academy Awards and he had this idea. Marvel had had an idea but then they scraped it and I thought it wasn’t going to happen. Then I saw Robert and he said, ‘What do you think about coming and doing a day?’ I said, ‘Are you kidding me? Bang, lets do it!’ We sort of spitballed that scene, then I came in and we shot for a couple of hours and laughed. I haven’t seen it yet but people seem to like it.”

I love hearing that Marvel’s creative process is so collaborative. In my experience, a project turns out much better when everyone involved has a say in the finished product, so seeing that Ruffalo and RDJ just played around a bit for this scene and then Marvel went ahead and used it puts a smile on my face, as I’m sure it did to many, many fans all over the world when they first saw it.

When pressed for information on any other cameos in Phase Two before Joss Whedon’s follow up in 2015, the actor was uncertain about that and said, “I don’t know, maybe, maybe not…They haven’t talked about it with me…”. And even if they did, he wouldn’t tell us. C’mon, you know how this works by now…

Even though we know how it works, we can still dream! Do you think that Mark Ruffalo’s Bruce Banner will pop up again before ‘The Avengers 2’? What did you think about his appearance in ‘Iron Man 3’? Share your thoughts in the comments.