Split your data into ping packet sized chucks and throw them out on the Internet. Keep all your data bouncing around on the Internet and use that as your storage provider.
My personal favourite was sending data in outgoing emails to invalid destinations. Your data would get queued and a few days later you'd receive it back in an undeliverable-message.
However this stopped being effective when mailserver stopped sending back the complete body of the bounced mail. Instead just a "Your mail couldn't be delivered, blah blah". You could deal with that by encoding your data in the subject-lines, though I guess ..
Split your data into ping packet sized chucks and throw them out on the Internet. Keep all your data bouncing around on the Internet and use that as your storage provider.
Not really practical, but a neat idea. Saw in the excellent "Silence of the wire": https://www.nostarch.com/silence.htm