How to make a foil packet: 

Lay a large sheet of heavy-duty foil or a double layer of regular foil on a flat surface.  Put the ingredients in the center of the foil. Bring the short ends of the foil together and fold twice to seal; fold in the sides to seal, leaving room for steam. Grill as directed.

For Shrimp:

Mix butter, parsley, garlic salt and pepper. Toss with the juice of 1 lemon, shrimp and a big pinch of red pepper flakes. Divide between 2 foil packets. Grill over high heat, 8 minutes.