Clarence Albert “Circus” Ferguson is one of Francis's delinquent friends, seen in season 1 with Justin and Richie
He doesn't ever speak, but seems to agree with Justin who usually says, "You the Man, Francis!" and instead is usually seen with a crazy look in his eyes. He once ate a dog food sandwich as a trade for Dewey's bike in the episode Smunday and is later seen riding it in the same episode.
In the episode Casino it was mentioned by Richie that both he and Justin were arrested for attempting to steal a giant inflatable panda from a car lot. Afterwards he was never seen or mentioned again so it’s likely that he and Justin spent the rest of the series incarcerated