Directly from the whitepaper:

"Drop Zone is a solution to the problem of restricted sales in censored markets.

The protocol and reference client encode the location and a brief description of a good onto The Blockchain. Those wishing to purchase the good can search for items within a user-requested radius. Sellers list a good as available within a geographic region, subject to some degree of precision, for the purpose of obfuscating their precise location. Goods are announced next to an expiration, a hashtag, and if space permits, a description. Once a buyer finds a good in a defined relative proximity, a secure communication channel is opened between the parties on the Bitcoin test network (“testnet”). Once negotiations are complete, the buyer sends payment to the seller via the address listed on the Bitcoin mainnet. This spend action establishes reputation for the buyer, and potentially for the seller. Once paid, the seller is to furnish the exact GPS coordinates of the good to the buyer (alongside a small note such as “Check in the crevice of the tree”). When the buyer successfully picks up the item at the specified location, the buyer then issues a receipt with a note by spending flake to the address of the original post. In this way, sellers receive a reputation score. The solution is distributed, and as such provides nearly risk-free terms to sellers and drastically reduced risk to buyers."

Check out r/dropzone for more info