Miracle Berry Tasting

I can't see much of an application for this other than as a party trick.

The Miracle Fruit plant (Synsepalum dulcificum) produces berries that, when eaten, cause bitter and sour foods (such as lemons and limes) consumed later to taste sweet. The berry, also known as Miracle Berry, Magic Berry, or Flavor Berry, was first documented by explorer Chevalier des Marchais during a 1725 excursion to its native West Africa.

Read more about it.