Removing a stripped lug nut without tools can be challenging. One method is to use a flathead screwdriver and a hammer. Place the screwdriver in the stripped groove and tap it with the hammer to create a new groove. Then, try turning the lug nut with the screwdriver. Alternatively, you can use a rubber mallet to hit the lug nut from different angles to loosen it. If these methods fail, it might be best to seek professional assistance.