Final answer:
Rocky exhibits being socially adaptable by making a lot of new friends and enjoying himself at a party despite not initially knowing anyone there.
Step-by-step explanation:
Rocky demonstrates the character trait of being socially adaptable. When he found himself at a party where he didn't know anyone, instead of feeling uncomfortable or out of place, he made the best of the situation. His ability to make a lot of new friends and have a great time despite the unfamiliar setting and absence of his cousin indicates that he is an outgoing and confident individual who is able to connect with others easily.