6. Opposite Day – season 1, episode 9b:
Nothing short of a classic, Opposite Day is one of the older episodes on this list, clocking in at episode nine of the entire series. Squidward is trying to sell his house to escape his neighbors, and so he tells Spongebob that it’s “opposite day,” in hopes that his natural personality won’t distract the realtor.
Little did he know what Spongebob’s complex reasoning would lead to:
“I don’t get it. I made my house a mess, which was making it clean, which made Squidward clean my yard, but that really means he’s messing it up. But the opposite of clean is filth, which means filth is clean, that means Squidward is really making my yard a wreck, but I normally wreck my own yard which means, Squidward is being the opposite of Squidward which means he’s SpongeBob! A-ha! I understand everything now! I must be the opposite of SpongeBob! By being… Squidward!”
Similar reasoning makes Patrick and Gary impersonate Squidward as well, terrifying the realtor and dooming Squidward to a life on Conch Street. Opposite Day is one of the best episodes of Spongebob because of the perfect blend it has of silliness, uniqueness, and in 2011, nostalgia.