The Unicorn Frappuccino was a huge hit for Starbucks and since then, other "secret menu" drinks like the Dragon and Mermaid Frappuccino have been all the rage. Now there's a new "must try" drink on the menu for a limited time. The Midnight Mint Mocha Frappuccino just went on sale! It's made out of coffee, extra-dark chocolate and mint sugar crystals, and it has whipped cream in the middle and on top.