I have found 2 episodes of SpongeBob SquarePants that heavily reference lucid dreaming. The first and more major reference is less of a reference and more of an episode about lucid dreaming. The first episode being called "Sleepy Time". In this episode, SpongeBob gets flung out of a dream he has into some small, glowing dream version of himself. He then visits other character's dreams. More lucid dream related, SpongeBob visits Patrick's dream, where he tells Patrick " This is a dream! You can do whatever you want. He then makes himself grow to the size of a skyscraper and then multiply himself a hundred times in a crowd around Patrick to demonstrate his dream powers. This episode was aired on the year 2000 and 16 years later, the other reference appeared in the episode "CopyBob DittoPants". In this episode, Sqwidward is convinced that the events of the episode are just a dream and he can do anything without consiqence. He later runs outside so he can do something he always wanted: to fly. That is all for lucid dreaming in SpongeBob I know of.