Mix the mayo, green onion and Gallopin' Gourmet Shake in a bowl and let sit in the refrigerator for an hour (you can also make overnight).
Take a 2" round cookie cutter and cut circles out of the bread slices. You can usually get 3 to 4 to a slice (make bread crumbs with the remaining bread or give the extra bread to the birds or the dog).
Spread a little of the mayo mixture on to the bread round and then place a shrimp on top.
Add a little snippet of parsley in the center. That's it.