Duncan Bubble is one of the main characters of Detention. He is quiet boy who is always playing with a yo-yo. He never speaks, instead using his yo-yo to spell out messages, accompanied by an electronic voice (done by Tom Kenny) reading the message.
Duncan wears a blue hat and a long sleeved blue turtleneck-ish shirt. He also wears glasses and has a cartoonish sized nose. He also wears black shoes and black pants. He always carries around a yellow yoyo.