Robert Downey Jr. and Chris Evans may be done with the Marvel Cinematic Universe, but they certainly aren't done being friends with each other.In celebration of Evans' birthday, Downey Jr. shared a gif from their latest film Avengers: Endgame. In the gif, Captain America looks down at a past version of himself in the aftermath of 2012's Battle of New York. Acknowledging Ant-Man's compliment from just a few scenes earlier, he nods and agrees, "That is America's ass."RELATED: Hemsworth's Fat Thor Belts Out Johnny Cash Song in BTS Endgame Video"Happy birthday to America's ass. The world's a better place, and I owe you a kiss on the cheek!" Downey Jr. wrote. Evans offered a simple response: a crown emoji and a blue heart.

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Today, Evans turns 38. The actor made his MCU debut eight years ago in 2011's Captain America: The First Avenger when he was 30. With Endgame, he chose to retire from the role of Captain America. His character also retired, using a time travel mechanism to go back and live his life in full. Downey Jr.'s Iron Man wasn't so lucky; the MCU's foundational character died when he used the Infinity Gauntlet to stop Thanos once and for all.

Directed by Joe and Anthony Russo, Avengers: Endgame stars Robert Downey Jr. as Iron Man, Chris Evans as Captain America, Mark Ruffalo as Bruce Banner, Chris Hemsworth as Thor, Scarlett Johansson as Black Widow, Jeremy Renner as Hawkeye, Brie Larson as Captain Marvel, Paul Rudd as Ant-Man, Don Cheadle as War Machine, Karen Gillan as Nebula, Danai Gurira as Okoye and Bradley Cooper as Rocket, with Gwyneth Paltrow Pepper Potts, Jon Favreau as Happy Hogan, Benedict Wong as Wong, Tessa Thompson as Valkyrie and Josh Brolin as Thanos. The film is in theaters now.