Justin, portrayed by Justin Pierce, is a friend of Francis. He can be seen in the episodes: Smunday and Home Alone 4, usually with Richie and Circus, saying his signature catchphrase, “You the man, Francis/Richie/Circus” etc.
Justin was arrested along with Circus for stealing a giant inflatable panda from a car dealership shortly before the events of Casino. He was never seen or mentioned again in the remainder of the series so it’s heavily implied that both he and Circus spent the rest of the series incarcerated.
It’s also implied that since Justin’s actor Justin Pierce passing away on July 10, 2000 shortly after the first season finale aired.