Bewitched 7x14

Endora presents an idea for a great campaign for the Bobbins Bon Bons account, and Bobbins takes a liking to her. He insists that she promote her idea on a TV show, which she refuses due to a ski date. So Samantha poses as Endora, but the deception is short-lived when the real Endora appears, magically, on live TV. Because of the special effects, Bobbins is sold on the idea.