Which opera song is being sung in the new Taco Bell triple steak?

"Vesti la giubba" (Put on the costume) is a famous tenor aria from Ruggero Leoncavallo's 1892 Opera Pagliacci. "Vesti la giubba" is the conclusion of the first act, when Canio discovers his wife's infidelity, but must nevertheless prepare for his performance as Pagliaccio the clown because "the show must go on".