During the show, McCartney invited a young fan, Leila, onto the stage, reported Entertainment Weekly.
The musician asked if she wanted him to sign her doll, but she had a more ambitious request.
"I want to play the bass with you," she said.
A surprised McCartney agreed.
"This could be interesting," he said.
A white bass guitar, almost the size of the youngster, was quickly brought out for her as the two went on to jam to the Beatles' classic, "Get Back".