Mayor Bill de Blasio's unorthodox method of eating a pizza irked New York's resident "pie expert" Jon Stewart.

"The Daily Show" host went off on the mayor during Monday night's show after de Blasio made headlines for eating a pizza at a Staten Island restaurant last week with a fork and knife. Stewart jokingly cursed at de Blasio's eating habits.

"You're supposed to be champion of the middle class. Two weeks into your term, and we catch you eating pizza a la [Donald] Trump?" he said as a split screen picture of the mayor and the real estate mogul popped up.

Two months ago, Stewart went off on how New York City pizza is better than Chicago style pizza in light of the feud between the two cities over the height of One World Trade Center.

De Blasio said using the fork and knife stemmed from his Italian heritage, but Stewart wouldn't accept his answer.

"Were you elected the mayor of Italy? Look out the window. You see the Sistine Chapel or Leaning Tower of Pisa? No, you don't," he said.

De Blasio's office declined to comment about Monday's episode.