Icky tends to bite his nails when he becomes nervous because it calms him down. nicky's behavior is an example of

Compulsive habit. This specific habit is known as onychophagy and it is a red flag for underlying disorders, such as OCD or anxiety. The onset of this habit is often occurring at a young age, and is categorized in the DSM-IV-R as an obsessive-compulsive disorder. In order for Icky to quit the habit, which is deleterious both for his nails and digestive system, he might need to get therapy, which solves the underlying causes