This tool allows you to smear an image. The effect on the color values of the image is determined by the brushstroke used and amount of pressure selected. A larger sized brush will smear a greater amount of color and a higher pressure will redistribute the color over a wider range.
Click on Smudge on the Tools bar.
In the "Smudge Options" dialog select a size and shape for the brush (see Brushes).
Use the slider to set the pressure in the Pressure box.
Proceed to drag the Smudge pointer through the appropriate areas of the image.
See: