Antonio is a busboy whom George got fired from his job in "The Busboy"; Antonio was played by David Labiosa.
One evening while George, Jerry and Elaine are out to dinner, they notice a menu has caught on fire. They rush to put it out and tell the manager that the busboy might have put the menu too close to a candle that was on the table, with Elaine jokingly stating that she'll never eat there again. The busboy, Antonio, gets chewed out by his boss, and is fired.
George feels very guilty, thinking he got the busboy fired. George, along with Kramer visits Antonio at his apartment so he can apologize for getting him fired. While they are in the apartment, Antonio's cat runs away, as Kramer had left the door open. They help Antonio look for the cat, but to no avail.
Later, Antonio shows up at Jerry's apartment, and George is terrified that he is there to "settle the score." However, Antonio informs him that there was an explosion at the restaurant he was just fired from, and five people were killed. If it weren't for George getting him fired, Antonio would've died as well. Antonio emphatically thanks George, and informs him that his cat came back and that he has gotten a new job. On his way downstairs, Antonio runs in to Elaine's boyfriend, and the two get in a fight. They are apparently both seriously injured, because George has to go take care of Antonio's cat while he recovers.