Hoax Photoshop work can get tedious to those of us who have to grade it. If you introduce the concepts of surrealism and narrative art you can get more thoughtful work. This set of flickr photos by J.R. Benzel (Justin Benzel) should be a good starting place to inspire your students. The one above is titled: "Handheld Teleporter Blues".
This would be easy to do with Photoshop. Demonstrate cutting and pasting, adjusting the light of the new pieces to match the original, and then how to use the clone tool.