Dad Man Walking is the third part of the 3rd episode in season 4 of Dexter's Laboratory, which aired on May 2, 2003. In this episode, Dad stumbles into Dexter's laboratory while sleeping. Dexter must try to get him out without waking his father up, but the task proves to be difficult.
Dexter's father sleepwalks into Dexter's lab. Dexter discovers this, and now has to escort him out of the lab without waking him up, which proves more difficult than thought.