The above is miracle fruit (http://en.wikipedia.org/wiki/Miracle_fruit). It contains a protein called miraculin that changes the way your taste buds perceive flavor, particularly sour flavor. My neighbor grows this fruit for fun and I got to try it a little while back. You pop it in your mouth, chew the pulp, and spit out the seed. Then you try as many different things as you can before the sensation disappears in half an hour or so. It makes lemons taste like lemonade, and vinegar taste like juice. So strange!
