McDonald's gave customers a lesson in supply and demand, compelling them to stand on line for a one-day revival of its Szechuan Sauce.

But many were left sauce-less, and some didn't receive their "limited-edition poster".

Dipping sauce-starved patrons queued up for blocks at various McDonald's across the US, including in New York, where Comic Con was unfolding over the weekend.

Police were called in Los Angeles and in Wellington, Florida, where crowds got boisterous upon learning there was no more sauce.

McDonald's responded with a promise to bring back the sauce - designed to go with the new Buttermilk Crispy Tenders - in the winter.

On Sunday, the fast-food giant posted on Twitter: "You spoke. We've listened. Lots more #SzechuanSauce and locations. Details soon.

"Yesterday, we were truly humbled by the amazing curiosity, passion and energy this community showed to welcome back Szechuan Sauce. Between the costumes, the memes and the cross-state travel, you, the fans, showed us what you got. And our super-limited batch, though well-intentioned, clearly wasn't near enough to meet that demand. Szechuan Sauce is coming back once again this winter."

McDonald's describes the sauce as "savory and slightly sweet sauce with hints of soy, ginger, garlic and slight vinegar notes".

Now, a 1-ounce packet of the scarce sauce is going for more than $200 on eBay. The ones on offer in the $100-to-$200 range had around 30 bids apiece.

But the real prize was a 16-pound container of the sweet-and-spicy stuff, on auction for $17,900, and it had 98 bids!

The social media hype for the sauce - and disappointment - was fueled by fans of the animated sci-fi sitcom Rick and Morty, part of the Cartoon Network's Adult Swim lineup, which referenced the sauce in April.

Rick, an alcoholic mad scientist, said the sauce gave him inspiration in life. A change.org petition soon followed, imploring McDonald's to bring the sauce back.

That social media passion turned to rage when sauce-deprived customers took to Twitter to denounce McDonald's over the weekend, with some calling for a boycott and class-action lawsuit, while others said it was all a publicity stunt.

The original Szechuan Sauce was rolled out in 1998 - to coincide with Disney's animated movie Mulan.

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(China Daily USA?10/11/2017 page2)