Here's a quick and easy way to fold a napkin into a Christmas tree shape:
1. Take a square napkin and fold it in half diagonally to make a triangle.
2. Fold the bottom edge up so that it reaches the top point of the triangle.
3. Fold the right edge over to meet the center line, and fold the left edge over to meet the center line as well.
4. Fold the top point down to create the top of the tree.
5. Fold the bottom edge up again, this time creating a point at the top.
6. Repeat steps 2-5 for the other side of