Liquid nitrogen is very cold. It can cause frostbite which is most commonly known as cold burn. This can result in serious injury and damage to body. So, always wear safety gloves when working with liquid nitrogen. If cold burn occur then visit to doctor immediately. Treatment of cold burn is same like that of sunburn.
Depends what state the nitrogen is in. Your touching nitrogen every second of everyday of your life. You have nitrogen in your body, and over 70% of the air around us is composed of nitrogen. If your talking about liquid nitrogen, then it will freeze your skin solid. You'll get severe frost bite and probably lose any part of your body it comes in contact with.