2 lb bag of cat poop (link goes to regtetsy archive of auction)
"returns are only accepted if an item has been grossly misrepresented."
Oh good, because I was worried that I might get something like an iPod instead of my Bag of Poop.
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And, for the less gross / tangibly related (PayPal)
PayPal makes buyer destroy $2,500 pre WWII antique French violin after item's authenticity is disputed by buyer (spoileralert/TealDear, it was real and seller is screwed).