CUT a square of parchment, available in supermarkets. Fold the square in half diagonally, then cut on the fold to make two triangles.
PLACE the long edge of one of the triangles so that it faces you, then lift the right-hand point, curling it so it lines up with the top of the triangle.
HOLD the first point in place, then bring the left-hand point of the triangle around the cone. Make sure the cone's nose is closed.
MAKE several folds at the top and tape the outer seam. Fill the cone and snip off a tiny bit of the nose. Presto! Squish the frosting through the opening.