Explaining Cartoons on Instagram: "The “F.U.N.” episode kicks off with Plankton’s latest attempt to steal the Krabby Patty formula going wrong, leaving SpongeBob feeling sorry for him. Deciding that what Plankton really needs is a friend, SpongeBob takes him out for a full day of “fun,” complete with jellyfishing, blowing bubbles, and riding Glove World–style attractions. This all builds into the legendary musical number spelling out F is for friends who do stuff together, U is for you and me…,