The phrase "bites nails" can have various antonyms depending on the context it is used in. If it is used to describe a nervous behavior, then its antonym could be "calm" or "relaxed." On the other hand, if it is used to express anxiety or stress, then its antonyms could be "composed" or "assured." Another possible antonym could be "hands-off," which suggests a nonchalant or disinterested attitude towards a situation. Similarly, "unworried" or "unconcerned" could be appropriate antonyms for the phrase, suggesting a lack of nervousness or anxiety. Overall, the antonyms for "bites nails" depend on the specific message that needs to be conveyed.