After introducing her, Fallon explained to the actor that viewers had been revealing their unknown talents to him.
This prompted Bell to say she wanted to show him her own talent: separate control over her eyeballs.
She then leaned closer to the camera and demonstrated how she is able to make her eyeball move in different directions to each other.
“Woah... wow!” Fallon exclaimed, asking Bell how she realised she was able to do it.
“I’ve always felt it was a separate muscle and I could always tap into them... but I guess I assumed everyone else had that too, and once at high school I did it and my friends were like, ‘woah!’” Bell said.
“Then I realised not everybody has it and I’ll be able to apply it to absolutely nothing!” she joked.
Later in the interview, Bell discussed her return to Gossip Girl for the HBO Max revival. Bell, who narrated the original series, is one of the few actors returning to the franchise. The series airs from 8 July.
“I love [voiceovers] – I like the challenge of having to evoke emotion from the audience using only one tool,” she said. “The new show is really cool because it talks about how social media has changed us, it’s more risque, and there’s a twist at the end of episode one that’s really different.”
You can read about the first trailer from the series here.