When purchasing a pack of cards, some Squinkies, or Shopkins, you could never be sure about what exactly you were going to get. There is a vast appeal in the blind bag, an appeal that still persists in the form of gambling, subscription boxes and even Tinder.

Life in plastic just got a little more fantastic. In an effort to boost its steadily falling sales, Mattel has broadened its Barbie dolls’ appearances to include four different sizes: original, curvy,...