MasiHosseini
Krabby Patty Burglar

I have a theory about Spongebob's brain. I think it was alive. Check the earlier episode Plankton!:

In this episode Plankton tried to control Spongebob's brain to get the krabby patty. I think Spongebob's brain kinda defected due Plankton's actions in this episode.
In Squilliam Returns:

Due Spongebob's defected brain he killed al his mini Spongebob workers.
In Fear of a Krabby Patty:

Plankton was testing Spongebob's memory and intelligence (next to his so called ''Krabby Patty Phobia.''
In Penny Foolish:
https://www.youtube.com/watch?v=u-nV7KIqhXc
His brain got legs (due Plankton's Total Control machine) and tried to go to the Chum Bucket.
In Stuck in the Wringer:

Spongebob's brain got eyes and a mouth (for a short time) due Plankton's actions.
In Inside Job:

Spongebob's brain kinda improved and it tried to make mini Things inside (not perfectly like in Squilliam Returns).

Plankton also sucked accidentally all his evil things in Spongebob's brain (what he did in Plankton!).
In later episodes:

His brain became kinda normal. In the pre-movie era the consequences of his brain damage was not intense. That explains he was kinda dumber in later seasons. In season 8 and 9 Spongebob got more intelligence again and less controllable because Plankton's sucked the evil things out in The Inside Job.
What do you guys think? :P