This is one of my favorite and somewhat unusual hor d'oeurves.
Cook a box of the huge shells. Drain and cool.
Mix 1/2 cup Hellmans Mayo and 1/2 cup sour cream. Add 1/4 cup chopped parsley and 1/4 cup chopped chives. Add squirt or two of fresh lemon juice and few drops Worcestershire sauce. In the bottom of each shell put in two smoked oysters (after blotting up most of the oil from the tin), then put spoonful of the mayo mixture in each shell. Garnish with parsley.

You can make this a day ahead and refrigerate. Amounts are all approximate. I usually cook 2 boxes of the shells cause some of them break or tear during cooking.