You call dibs on something by making a post calling dibs somewhere with a timestamp that will be trusted.
You can edit wikipedia, push to git repo, tweet about it, or post about it on facebook. Then you keep the link to that somewhere safe. For additional security you can put the claim of dibs in multiple places.
This is America, you can sell anything. If you sell your dibs simply edit (or add a second tweet) stating that you have sold your dibs and who you have sold it to.
Yes. Dibs is about trust and respect for decorum. It is important that scammers and con artists are not allowed in the space. They should be tarred and feathered.
I call dibs on cute cat pictures. If someone posts a cute cat picture it’s mine see my git repo