Don't get surprised and judge my photoshop talent before I tell the truth :p. Trust me! you no need to use photoshop or other complicated softwares to mock images. I recommend FaceOnBody software with which you can replace the faces of your friends with famous characters and thus astonish your buddies. Get the trial version of the software from Here, Usage of the software is really simple, try to get the crack by googling or PM me. For more queries comment here.