Step-By-Step Instructions:
1. Open a high resolution photograph of a person's face in Photoshop.
2. Goto Layer > Duplicate Layer... and click OK when the Duplicate Layer pop-up appears.
3. Turn off the visibility of the bottom layer by clicking the "Eye" icon for that layer in the Layers Palette.
4. With the new duplicate layer selected, select the eraser tool and erase everything except the mouth and some of the skin that surrounds the mouth.
5. Turn on the visibility of the bottom layer by clicking the "Eye" icon in the Layers Palette.
6. With the bottom layer active, click CTRL+T to enter into Free Transform mode.
7. Use a corner shape handle while holding down the shift key and drag to shrink the image.
8. Select the layer with the mouth and move it over the area where the mouth should be.
9. Goto Layer > Flatten Image to merge all the layers.
10. Select the Smudge Tool and choose an appropriate sized brush.
11. Carefully smudge around the mouth so that it blends with the face.
12. You're done! Your image should be a little smaller than the one you started out with, due to the resizing in Step 7.
