The Challenge (1998)

S2E7 Percy and the Signal

Percy enjoys pulling pranks on the larger engines, like convincing Gordon that he's running behind schedule and telling James he can't depart the sheds due to an impending inspector visit. Fed up with his antics, Gordon and James devise a scheme to get back at him by feeding him the outrageous concept of "reverse signals." They plan to play along with Percy's confusion, leading to a hilarious turn of events as he tries to navigate the absurdity of their trickery.