Some of the subtle jokes and references?
From time to time, I'll see an episode that I've already seen a dozen times and I'll pick up a joke or a reference to another show that I'd previously missed or didn't pay attention to.
Some examples:
In the episode with the claw machine, the machine calls for Squidward the same way as a slot machine in a Twilight Zone episode. In the TZ episode, the machine says, "Frank-lin" the same way the claw machine says "Squid-ward." I don't know why I never noticed that one before.
In the Whirlybrains episode, when Patrick loses his brain, he starts saying "M-O-O-N" the same way Tom Cullen said it in "The Stand." Patrick and Tom Cullen are both played by Bill Fagerbakke.
Have you seen others?
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I blame autocorrect.
You may all go to hell, and I will go to Texas.