Above the throng shoving its way along Via dei Tribunali, this pizza-crazed city’s historic pizza thoroughfare, Antonio Borrelli leaned over the fake lemons hanging from the “Balcony of Song” above Antica Pizzeria Gino Sorbillo and dared sing something else. “The pizza!” the crowd screamed in protest.

“The pizza. O.K., O.K., O.K. Give me a second,” Mr. Borrelli, a local crooning attraction, said on Friday as he switched the track on his sound machine, gripped the microphone and, with an intro of “Everybody, here we go again,” sang: “But you wanted the pizza. The pizza. The pizza. With the tomato sauce on top. With the tomato sauce on top.”