The one I remember best is where Darla made Alfalfa a cheese sandwich, but he was pranked by Spanky substituting slices of soap for the cheese. Of course, Alfalfa started blowing bubbles when he opened his mouth to sing in a school pageant (for Valentine’s Day, I think).
Well, that’s what you get for turning traitor on the He-Man Woman Haters Club.
(IIRC, there was also a cream puff filled with soft soap lather.)