I (no joke) have this fantasy/fixation on a scenario where I tie someone down and turn their elbow and knee joints into pulp using a hammer. Then I cut halfway into their femur (right about level with the groin) and see if I can't break through the rest of the femur just by using my body weight or with swings of the hammer. Sometimes I leave one leg intact because I like the idea of breaking the body's symmetry. The lower leg I typically leave alone, but I usually destroy the ankles in some way that does not use the hammer, like using clamps or a vice, or even going back to the saw.
Moving upward, I use the saw to cut in the spaces between the fingers on one hand. I saw down until I hit the carpals, then I use my hands to spread the fingers apart as far as possible. On the other hand I cut diagonally, leaving the thumb intact. I'm not quite sure why I do this because it's not particularly interesting. I forcefully press down on the ribs on one side of the chest to see if I can break them. In some less likely versions of the fantasy there are incisions made and the ribs are manipulated from there.
I leave the head alone for now and return to the lower body, except I turn the person over so I can work on the spine. I use the saw to expose the lower spine and then iteratively hit it with the hammer, between strikes checking the legs to see if there is still any response. Once there is no response, I do the same to the upper body. Once I'm sure that the rest of the body is completely paralyzed and incapable of further pain, I move onto the head. Doing the spine thing will ensure that all further pain felt by the head will be untainted by the pain going through the rest of the body. My plan with the head involves striking the jaw on one side of the head and dislocating it, and then doing the same with the other side. After that, I'd try kicking the now-loose jaw to see what happens, whether it will be removed entirely or just stretch or just send a bunch of teeth flying across the room. Then I'd pull the jaw down as far as I could, and put my foot in the mouth sideways, with my foot going horizontally into the mouth. I'd then press down as hard as I could to see what would happen. After this, I'd break the nose. Moving along, I'd shave the head and use a penknife to cut a pinhead-like grid into the skull, down to the bone. With an open palm, I'd rub over the squares to see if they'd rip off or what.
I'm not a killer, so after I got bored I'd dump the body in a deep drainage ditch along the side of the road, or maybe in the concrete island between two medians on the road.
