Valentines Day is (the first half of the) sixteenth episode from the famed Spongebob Squarepants, and my favorite Spongebob episode of all time. So many iconic moments come from this one episode. It features some of the best designs, character and background, of the entire show. It's also the debut episode for a lot of the "incidentals" aka background characters (including my personal favorite Dale).
The background artists were fucking cooking when they made this episode, because every single location is crafted with such love and care. Especially the carnival, which is where most of the episode takes place. Everything is red and white and covered in hearts, and I love it. You can see every individual brushstroke in each individual animation cel. My favorite attraction is probably the Madame Fishy Fortune Teller (that heart eye sign is so I iconic I want it tattooed on my body), although the rollercoaster is a close second. The characters have that iconic Season 1 design that so many old fans, including me, love. I'm especially fond of Patricks white heart shirt and the carnivals silly little work uniforms.