MEMPHIS — The fans who pack FedEx Forum for Grizzlies games never know when it will happen. It could be a timeout late in the second quarter, or a break in the action early in the fourth. It does not even occur every game.

But when it does, and the sweet beat of the Miami Sound Machine hit “Conga” fills the arena, everyone knows to look up toward the giant video board that looms over the court. A set of cartoon bongos appears, and as various fans pop up on the screen in their haphazard attempts to play them, Malenda Meacham, a longtime season-ticket holder, knows that they are merely the warm-up act.

The moment is about to belong to her.

“Bongo Lady,” the Grizzlies’ Tony Allen said, “is my home girl.”

Meacham, 45, might just be the world’s pre-eminent air-bongo impresario. She flails her arms and bobs her head as she plays the heck out of those cartoon bongos, her movements defying easy description.