As soon as the news that McDonald's was (sort of) bringing back Szechuan sauce hit, it was pretty obvious fans would go wild.
But few could have predicted that would translate to one fan snapping up a bottle for $15,350 ($A19,443), The Sun reports.
The sweet and sour sauce, which shot to fan when it was mentioned in the third series of adult sci-fi cartoon Rick and Morty, is now at the centre of a fight between its owner and the winning bidder, who has apparently gone to ground.
Writer Robert Workman got his hands on one of the bottles and put it on ebay. It attracted plenty of attention and eventually sold for five figures.
But Workman said on Sunday that the winning bidder had disappeared and failed to follow through with the purchase.
On YouTube, he said he planned to use the funds raised to "do a lot of good" for charity, but "unfortunately ... the head buyer welched".
"He did not want the sauce, he did not contact me in any way ... we have not heard back and there's a possibility we may not hear back.
"He's sitting on a bunch of ebay fees and it's kind of disappointing. We're left hanging."
The special sauce was added to the menu for a limited time in 1998 to promote Disney's Mulan film, but after TV fans heard the name-check they began to call for it to make a comeback.
McDonald's listened, and after gifting a super-size portion to the cartoon's co-creator Justin Roiland, the chain gave bottles to three lucky fans too.
In the ebay listing, Workman said: "It's being sold here to settle some bills and help out a couple of charities in the process.
"The auction includes a NEW, SEALED 64 oz. bottle of the special sauce (which isn't being made right now, so it's VERY rare), along with a special Rick and Morty inspired Pelican camera case, which houses the sauce."
He said he originally expected to sell the sauce for $20,000 but "the sauce is still here".
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