Fox's long-running hit animated series The Simpsons airs a new episode tonight, "Grampy Can Ya Hear Me," featured an unusual shout-out to another animated series, Adult Swim's beloved show Rick & Morty. Longtime Simpsons producer Al Jean sent out a screenshot from the episode that features young Maggie holding up a bottle of szechuan sauce, an homage to a recent Rick and Morty episode about McDonald's discontinued szechuan sauce. This series is just the latest to be referenced in The Simpsons, with the Season 29 premiere referencing Game of Thrones throughout the episode.

After debuting blurry screen grab on Twitter, The Simpsons showrunner Al Jean responded to a fan, confirming that the szechuan sauce bottle in the screengrab was, "a little shout-out" to Rick and Morty. The Rick and Morty Season 3 premiere referenced the szechuan sauce that McDonald's created as a limited-time promotion tied to the Disney animated movie Mulan. This actually lead to McDonald's caving to public demand, bringing back the sauce for just one day only on October 7, along with creating 1,000 limited-edition, hand numbered, screen-printed posters for all 10 sauces in our legendary lineup, including Szechuan Sauce. Here's what McDonald's had to say about the sauce before its return on October 7.

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"But, let's really talk tender...we know they're even better with sauce. We're introducing an all-new Signature Sauce to perfectly pair with them. Ready to celebrate? We're giving away 1,000 limited-edition, hand numbered, screen-printed posters for all 10 sauces in our legendary lineup, including Szechuan Sauce. That's right, collectible art, worthy of the pop-culture status fans have given their favorite sauces. In addition, after nearly 20 years (and perhaps a bit of time travel) we're even doing the impossible...On Oct 7, together with the collectible sauce-themed posters, we're also giving away a one-time only, limited-edition, run of Szechuan Sauce in select restaurants. And when we say limited, we mean really, really limited! Click below to find out which restaurants will be giving away* the posters, and the select few of those that will also have the Szechuan Sauce on Oct 7. So mark your calendars. It's time to show your flavor. Your passion.'re Obsauced."

Fox has already renewed The Simpsons for the current Season 29 and Season 30, which will ensure the series will become the longest-running series of all time, breaking Gunsmoke's record of 635 episodes. While The Simpsons had already broken Gunsmoke's record of 20 seasons long ago, Gunsmoke's seasons were much longer, which is why it has taken The Simpsons another 10 seasons to break the 635 episode mark, with the 30th Season taking the total up to 669 episodes. It hasn't been confirmed if that will in fact be the final season of The Simpsons, but with the show's place in the record books already set in stone, it wouldn't be surprising.

The Simpsons have been going through some unique changes, with the series firing longtime composer Alf Clausen after a whopping 27 seasons. Still, the hit series remains the anchor of Fox's strong Sunday night lineup after nearly three decades, although it will be interesting to see if we start hearing about the show's endgame soon. Take a look at these tweets from Al Jean's Twitter about this Rick and Morty shout-out.