Yogurt is made by culturing pasteurized milk with harmless bacteria (they're actually good for you), causing fermentation. This process gives yogurt its slightly tart taste and semi-firm texture; it's also what makes yogurt easy to digest.
In a blender, combine mango, yogurt, sugar, and 1/2 cup cold water. Pour through a fine sieve (to remove pulp), if desired. Serve immediately over ice.
Each batch serves only two so blender won't be filled more than halfway. Make more batches as needed.