Paul Rudd explains his 'Cheshire Cat' grin in Marvel Studios class photo

Forget Ant-Man: Paul Rudd’s superhero name should be Smiley Face. To mark its 10th anniversary as the dominant studio in the comic-book movie game, Marvel Studios recently released an all-star photo that assembled nearly every major costumed super populating the Marvel Cinematic Universe. And eagle-eyed fans immediately zeroed in on the fact that Rudd, who plays the pint-sized title character in the 2015 hit Ant-Man and its upcoming sequel, Ant-Man and the Wasp, wore a giant-sized grin as he sat among Avenger royalty including Robert Downey Jr., Chris Evans, Chadwick Boseman, and Scarlett Johansson, all of whom appeared a bit more restrained in their enthusiasm.

Like everyone else on the internet, we were charmed by Rudd’s elementary school-ready grin, so when we sat down with the actor to discuss his new film, Mute, which hits Netflix on Friday, we couldn’t resist asking him: Why so smiley? “We took about a hundred pictures,” Rudd remembers. “I’m sure that in some of the other ones, I wasn’t beaming and other people were! It just so happened that in the one they picked, everybody else was looking very serious and I’m sitting there grinning like the Cheshire Cat! All of that being said, it was very cool to be there. Stan Lee was sitting right there, and all the people from the movies. I remember thinking, ‘There are a lot of people in the world who would be interested to be in this room right now.’”

Turns out that one of those people is Rudd’s Mute co-star Justin Theroux, who joined our interview and confessed that he didn’t see the Marvel Studios photo in question when it hit the web a few weeks ago (to be fair, he might have been a bit preoccupied). It’s worth noting that Theroux deserved to have been in the room where the picture happened, since he co-wrote Iron Man 2 with director Jon Favreau, who appears between Angela Bassett and Chris Hemsworth in the shot. “Kevin Feige didn’t give me a call,” the actor remarks with a chuckle, making it clear there are no hard feelings about his omission. “When you have the whole cast of the MCU there, I think the main thing you want to see is the writer of Iron Man 2 front and center lying there like a cheerleader in the way of everyone.”

Since Theroux wasn’t present for the picture, Rudd helpfully pulled it up on his phone for his pal’s insta-critique. “Oh my God — it’s a third-grade photo! You should have a lunchbox,” Theroux hoots. But Rudd stands up for his goody-two-shoes smile in the face of his co-star’s good-natured ribbing. “The thing is, we did a lot of pictures in 30 minutes, and I remember that I had a little bit of ‘What do I do with my hands?’” he explains, making exaggerated gestures. “When they took this particular picture, everyone else looks relaxed, and I’m sitting straight up.” Besides, it’s not as if Rudd is the only person in his section of the class photo flashing his pearly whites. “Look! Jeremy Renner is standing next to me and also smiling,” the actor points out. “And Tom Holland is smiling too!” If you ask us, the trio of Spidey, Ant-Man, and Hawkeye would make for a pretty awesome live-action adaptation of Spider-Man and His Amazing Friends.

Read more from Yahoo Entertainment:

• Michelle Obama praises ‘Black Panther,’ celebrity Twitter agrees

• ‘Black Panther’ breakout Shuri crowned the best Disney princess by social media

• The biggest ‘Black Panther’ Easter eggs and end-credits scenes explained (spoilers!)

Watch: The Black Panther cast reveals why their film is Marvel’s most political ever: