In a blender add 3 cups of water, garlic cloves, pinch of pepper and salt to taste mix well until the garlic is completely  blended.  Pour the garlic mixture in a large bowl and add  the shrimp. Cover and let them rest for 5 minutes in the refrigerator ( that's all the time they need to marinade). In a large frying pan heat the butter until melted, keep the heat on medium low being careful not to burn the butter.  Once the butter is hot add the shrimp using tongues. Cook about 5 shrimp at a time, for about  2 minutes  on each side just until  they turn pink and curl. Be careful not to overcook the shrimp because they  will become rubbery.  Place them in a plate with paper towels and cover with aluminum foil until you finish cooking all the shrimp.