1. Make sure that you really want to cut off your thumb. You will be able to have it reconnected if you take precautions but it won't work as well as before. 2. Find a good knife. A large kitchen knife should work. 3. Sharpen the knife. A sharper knife will be able to cut better and cause you less pain. 4. Pick a thumb. If you are doing this to disable yourself, pick the thumb on your dominant hand, the one you write with. If you are doing this for entertainment purposes or as a political statement, choose the thumb on your other hand. 5. Spread a towel out on a flat surface. Spread the fingers on the hand you want to cut as wide as possible and place them palm-down on the towel. 6. Bring your non-thumb fingers together and pull them farther apart from the thumb. 7. Balance the knife diagonally over the joint in your thumb that is second from the thumbnail. The knife should run parallel to your index finger. 8. Hold the top of the knife blade steady with the top of your hand, the hand not being cut up. 9. Count backwards from five. 10. Press down on the knife with as much force possible. The knife will crunch through the joint and your thumb will stop being attached to your hand. 11. Use the towel to slow the bleeding. Hold the towel over the place where your thumb was. Press down on it. 12. Now that the thumb is off and the bleeding has been slowed, you require medical assistance. Call a friend or a taxi service to drive you to the hospital. 13. Fill a plastic bag with ice and put the thumb inside. 14. Walk around outside until your ride arrives. 15. Once at the hospital, tell them that you have removed your thumb and that you would like a doctor to put it back on for you.