SpongeBob SquarePants Season 13 Episode 20 Friendiversary / Mandatory Music Episode Title: Friendiversary / Mandatory Music Episode Description: Friendiversary:It's the day of SpongeBob and Squidward's "friendiversary," and SpongeBob continuously stalks Squidward around trying to celebrate and create more memories with him. The sponge's refusal to leave Squidward alone drives him to his edge, figuratively and literally erasing SpongeBob's knowledge of him. When Mr. Krabs reveals that SpongeBob's memories of Squidward keeps the Krabby Patty secret formula in check, the cephalopod's got to revive SpongeBob's recollection of him in a sequence of callbacks to various episodes from the past thirteen seasons of the series. Mandatory Music:When Squidward's awful clarinet playing ends up causing destruction and damage around town, he's forced to take music classes at Little Flipper Music Academy, in which he's constantly frustrated his by supposed lack of talent and the superiority of SpongeBob's "flute-nose" music technique.