Something I enjoy doing from time to time is using photos within other photos. I've basically done this to put parts of people's faces over other people's faces. Quite frankly, it looks hilarious and it's actually really simple to do. So the first step is just to take a photo of someone's face or eyes or mouth or whatever on your phone, or if you can be bothered, take one on your camera and then transfer it over to your phone or tablet. Then just hold this over the other person's face to mix their facial features together. Sometimes you can use your own face and zoom in on your phone/tablet to make it look larger. Try to zoom in and position your phone/tablet to try and line it up as best you can. To get an idea of what I'm talking about, here are some example photographs:
So why not give it a shot sometime. See how hilarious you can be.