Replace the face of a friend on your camera's phone with a famous person such as Obama. Or you can take a photo of a friend and use that friends face to replace the face of another friend. See what your friend looks like with faces swapped over. Theres many faces to choose from including Britney Spears, the Queen and Psy.
For the free version check out
Google Play.
For the full version which includes extra faces to choose from, no advertising and the ability to take a picture and save it to your gallery check out
Google Play.