Starbucks caused mayhem last week with the limited release of the visually cute af Unicorn Frappuccino. They came out on April 19th. I bought mine the next day and the Town Center store had already run out of the blue syrup (see my taste test here).
They only kept it on the menus until April 23rd but plenty of stores couldn't keep supplies to make them that long.
So if you missed the unicorn sighting (lol) or you want to recreate the basic-ness at home, watch a fairly easy DIY recipe above.