"hipsterDB is a key/value store that only returns data as long as it isn't mainstream. The more often that you access a key the more mainstream it becomes. After data has gone mainstream you will have to wait for it to go out of style before using it again."
From their Github README.md:
"hipsterDB is a key/value store that only returns data as long as it isn't mainstream. The more often that you access a key the more mainstream it becomes. After data has gone mainstream you will have to wait for it to go out of style before using it again."