Convert your pictures to Negative Grayscale (black and white, then the opposite)!
Ideas:
-make your friend look like a zombie
-make a nature picture look like an alien world
Instructions:
Step 1. Select a picture directly from your camera or gallery
Step 2. Filter your picture with Picture Negative Grayscale!
Step 3. Save a copy of the filtered picture back to your gallery
Step 4. Send your new picture directly to an email or another application