Community took three seasons setting up this Beetlejuice joke

Here, for your viewing pleasure, is the perfect example of why Community is one of the most brilliant and complex shows on television, and also the perfect example of why it is criminally underwatched and recently got bumped from NBC's Thursday night comedy block. A truly eagle-eyed viewer recently put this video up on YouTube, showing the Beetlejuice joke that the show — which wasn't even guaranteed a full-season run, if we're being honest — spent three seasons building towards. And it's a background joke that I bet almost everyone missed. (I know I did.)

The name "Beetlejuice" has been used once per season on the show, and the most recent came during the third season's Halloween episode, "Horror Fiction In Seven Spooky Steps." And what happens when we say his name three times, everyone? (Hint: watch behind Annie.)

Yeah, so, that kind of blew my mind? This is somewhat reminiscent of the episode in which Abed, arguably the show's breakout character, spent the entire half hour in the background, helping a woman give birth. (This show works hard so hard, people.) This makes me wonder, though: were the writers planning this since season one? Was it a happy coincidence that they had used the name twice, and they only realized the chance for a joke after the fact? I eagerly await Dan Harmon's response.