The 12 Years a Slave star admitted during a Jan. 22 appearance on Late Night With Jimmy Fallon that she had no idea the Saving Mr. Banks actress was behind her on the red carpet, much less making a fantastic funny face.
"I only learned that afterwards," the 30-year-old told Jimmy Fallon with a big chuckle. "Someone sent me the GIF and I was just like oh my god! I had no idea she was doing that."
The Oscar nominee, who looked radiant in a dark purple ensemble, also gushed about her accomplished family.
"Your dad is a senator?" Fallon asked Nyong'o. "In Kenya?"
"Yeah, he is," Nyong'o replied.
"Your cousin, Isis Nyong'o, is one of the 20 most powerful women in Africa by Forbes," Fallon said. "What does she do?"
"Something to do with technology," Nyong'o said. "She's just like amazing."
Another family member who is also amazing: her younger brother, Junior, who is a freshman in college.
"He sent out this video on Instagram, when you got nominated for an Academy Award. He wrote, I love, love, love my sister. #happy clap along if you feel like happiness is the truth."
"He's amazing," Nyong'o said of her sibling. "He lives in an exclamation point."
And we can clearly see why after watching this sweet clip!