Mister Rogers' Neighborhood (1968)

S6E4 Episode 4

Chef Brockett is excited about the idea of introducing a soda fountain at his bakery. Meanwhile, in the Neighborhood of Make-Believe, Lady Aberlin returns with a toy horse that, when you pull a string, exclaims, "I know." X gifts her a toy seagull that responds with "you know" when its string is pulled.