I noticed that in the episode Bucket Sweet Bucket, a lot of the main characters didn't know each other's names. Spongebob called Plankton "little green creature" and Plankton calls Squidward "the tall one". Spongebob does know Plankton's name later in the episode, but Plankton never seemed to learn Squidwards. However, they knew each other's names in many other episodes, including one before AND after it. Just thought I'd like to point that out.