Robert Downey Jr. took some time out of his day to wish his Avengers: Endgame co-star Chris Evans a happy birthday. Today, June 13th, is Evans' 38th birthday. Mark Ruffalo also has a message for the Captain America actor on social media, but his was a little more heartwarming than Downey Jr.'s. The Tony Stark actor is pretty quick-witted and he decided to pay tribute to Evans with a rather cheeky message, collecting some laughs from Marvel Cinematic Universe fans and the actor himself.

Endgame features a rather intense battle where Steve Rogers has to go up against himself. It's a pretty tough battle for the elder Rogers, but in the end, he prevails. Before he walks away, he looks at his younger self on the ground and admires his backside. Robert Downey Jr. chose to recognize this scene for Chris Evans' birthday message. He had this to say.

"Happy birthday to America's ass. The world's a better place, and I owe you a kiss on the cheek!"

Chris Evans responded by thanking Robert Downey Jr. with an emoji insinuating he's the king with a heart. Mark Ruffalo's message to Evans was a little more tender. "Happiest of birthdays to the fantastic Chris Evans. Love you, Bro. Always there when you need him. Wishing you all the best today!," said Ruffalo. MCU fans love to see their favorite superheroes interacting on social media and these guys don't disappoint, mainly because they actually like being around each other and consider themselves to be a family. Though one has to doubt Ruffalo's commitment since he hasn't joined the team and gotten his Avengers tattoo yet.

Avengers: Endgame saw Smart Hulk end up with some significant damage to his body after completing the first snap. Tony Stark, however, did not fare as well as Hulk did and ended up dying on the battlefield after performing a snap of his own. As for Steve Rogers, he ended up going back in time to spend the rest of his life with Peggy Carter. The actors had to keep these secrets from getting out for quite a while, which was not an easy thing to do, just ask Mark Ruffalo.

Since the spoiler ban on Avengers: Endgame was lifted, the cast and crew have been sharing pictures and video from the set, even though there was supposedly a pretty strict no-camera/phone policy. That obviously did not stop any of them from sharing pictures of each other on social media after the movie had hit theaters, giving MCU fans a glimpse of what it was like to make the movie. For having such a downbeat tone, the cast and crew all seemed to be having a pretty good time. You can see the birthday wishes to Chris Evans below, starting with Robert Downey Jr.'s Twitter message.