My brother is a routine criminal for biting his nails and sometimes the skin around his nails. Every time I am with my brother, I catch him biting his nails and/or fingers and usually reprimand him for his behaviour since he has experienced bacterial infections due to this unhygienic behaviour before. It is extremely unhealthy since there are deeply wretched germs and a paradise of bacteria lying underneath the nails which are eventually transmitted into the body system though the mouth. Nail biting can also cause serious dental damage, accidental trauma to the gums, unpleasant breath, and potentially cause the nail to never grow back again! Therefore, I have decided to observe my brother’s behaviour in the mornings and afternoons in an attempt to modify his unhealthy nail biting behaviour over the course of seven days using a series of positive and negative reinforcements.