Kidney

I sold my kidney online.
I mailed a certificate to the buyer's house, which stated that the kidney could be redeemed upon my death by natural causes.
“I need it now,” they wrote back.
“Tough luck,” I wrote in reply. “Maybe you shouldn't believe everything you read online.”

I'm pretty sure it was some organ-harvesting triad, anyway.
It suits me to believe this
because the alternative is I gave hope to someone who needed it,
then snatched it away.
And took their money, too.