Use some sort of filter to distort or alter your image. Explain your method of filtering in your post. Note: Must use physical filters, lenses, common household materials, etc. No in-camera digital filters or post-processing filters in Photoshop, GIMP, etc.
cameraflage: In-camera multiple exposures are always fair game, though I’m not sure how that would apply specifically to this theme. There is at least one camera out there now that can do in-camera HDR; I would consider that beyond the scope of normal Farktography rules.
corsec67: If there’s something filtering the light reaching your camera’s sensor or film (and yes, beyond the camera lens itself), then yes, it should be fair game.