You can easily use photo manipulation to make very trippy, surreal, drugged out, distorted faces. All you have to do is open your image up and select the face using the standard Rectangle Marquee tool. Then, go to Edit > Content-Aware Scale. Grab one of the points on the edge the selection and move it around. I like to shrink the face together rather than expand it, but feel free to experiment. The higher the resolution your original image is, the better quality it will be.
If you want to protect certain areas of your image (areas that will not be scaled) simply go to the Channels tab and create a new channel (Alpha 1). Then use a white brush to fill in the areas you want to protect. After you've done that, select your image using the Rectangle Marquee tool and then click Edit > Content Aware Scale in the menu.
Now, Below the main menu at the top there will be a toolbar, at the right of the toolbar there is a drop down box that is labeled "Protect:". Select Alpha 1, and then scale your image like normal. Keep in mind that none of the images on here were scaled using the Protect function.
Another awesome way to make weird faces is to scan your face!
You can easily make surreal face art just like these using your scanner. You can also use hands, pencils, and other various objects. Simply push the scan button and move your face along with the scanner light line. When you move your head along with the line, it will become stretched.
Pretty gruesome huh? The more you practice, the more you'll be making faces look completely mutated. These images came straight out of my scanner and have not been photoshopped in any way. You can see that the black background isn't 100% black. You can fix this in Photoshop by clicking on Image > Adjustments > Selective Color, once there, select Blacks as your color, and then move the slider to the right. This will darken your background substantially. If it isn't looking 100% black to you, click Image > Auto Contrast, and then try doing it again. It should work after Auto Contrast.
Have fun! Another way to make scary faces is to manipulate your face in CS4 using Content Aware Scaling.