I actually really liked seasons 4 and 5. 4 was the last genuinely great season in my eyes, and 5 was mostly pretty solid. It did have what's one of Plankton's funniest moments in my opinion (although we can't forget about the time he accidentally nuked Bikini Bottom in season 8). I speak of the time where he roasted an entire family.
I realize that song is a parody of Twisted Sister's I Wanna Rock, but still, definitely a banger. On that subject, Motorhead also did a version of one of their songs specifically for that movie, so that was pretty cool too.
Shitposts should be made the way God intended: while huffing Scotchgard and suffering from mononucleosis. Only in such a state of delirium can shitposting perfection be achieved. Although, if you don't have mono, just huffing Scotchgard while making them also works.