With a large chef's knife, remove kernels from corn cobs. With a butter knife, press and slide along corn cobs to remove liquid left in cobs. (NOTE: this should yield about 4 cups kernels and 1/3 cup liquid.)
Reserve about 1 cup of corn kernels. Working in two batches, blend in blender 3 cups of corn, liquid from cobs, yogurt, milk, lime juice and hot sauce. Strain through a sieve and discard solids. Taste and add salt and pepper as desired. Cover and chill for about 30 minutes.
Dice most of the shrimp, reserving a few whole shrimp as garnishes. Stir reserved 1 cup of corn kernels and diced shrimp into soup. Spoon soup into bowls and then garnish with reserved whole shrimp, diced tomato and avocado pieces. Serve immediately.