The Avengers: Endgame co-stars both sat down with Ellen DeGeneres on her daytime talk show on Tuesday, and hilariously came up blank when the host asked them to dish on when and how their friendship first began.
"You don't remember how we met?" Johansson asked, surprised.
"I do," Larson said, uncertainly. "I thought you didn't…"
When prodded by Johansson to share some details on how they met, Larson tried to vamp as best she could and offered, "At dinner?"
As it turns out, this was wrong and a jokingly offended Johansson exclaimed, "Clearly it made an impression on me but somebody else didn't care."
As it turns out, long before their first time grabbing food together, the pair actually worked together on the set of the 2013 rom com Don Jon.
"I didn’t even think about that because I just felt like I was basically a glorified extra and you were Scarlett Johansson," Larson said, bashfully.
"I noticed you, Brie. I noticed you," Johansson said with a broad smile. "You were not a glorified extra."
Long before he played Bruce "The Hulk" Banner and she was Carol "Captain Marvel" Danvers, they were both actors in the classic rom com 13 Going on 30.
However, when ET's Kevin Frazier caught up with the affable actor at the premiere of Endgame at the LA Convention Center on Monday, it turned out Ruffalo had absolutely no idea that Larson played a small role in the beloved comedy, and was blown away to find out that they'd worked together before.
Check out the video below to see the hilarious, heartwarming moment.