Jett's personality was not even or less described, except he's not interested at Diana, but only his girlfriend at the cafeteria.
Jett's appearance was shown as a slender and muscular student with brown hair with a spiked circuit, little thick brown eyebrows and blue eyes.
Role in the episode
At lunch in the cafeteria, Diana in line stands and shows Jett her moves to impress him after he stops walking to get his lunch, but he's not interested at her. When he asks Diana to go out and get some pizza with him after the game, she says she loves too after which shocked both Martin and Java and also, he holds his girlfriend's hand (who was the cheerleader) and walks to sit in the table after he says, "Excuse me.", after she gasps.