In GTA San Andreas, there is a glitch that will cause CJ to be able to run around without a head. To exploit this glitch, start a multiplayer game making sure player two has a Katana. When it starts have player two cut off player one's head with the Katana. This will cause the multiplayer session to end. Once it returns to one player mode, CJ won't have a head, and can stay like that for as long as the player desires, CJ's head back to normal in the cutscenes but return headless if the cutscenes end.
El Quebrados, Tierra Robada - Behind a small building in the trailer park in the north part of El Quebrados. From the El Quebrados Safehouse, head north and cross the street. Once you cross the street you should see a black, white, and blue trailer ahead of you. Go to the north end of this trailer and turn left. You should see a small building that does not look like a trailer. The Katana is at the north part of this small building.