Final answer:
The phenomenon described is the imaginary audience, which is part of adolescent egocentrism.
Step-by-step explanation:
The phenomenon described in the question is the imaginary audience, which is a part of adolescent egocentrism. The imaginary audience refers to the belief that everyone is constantly watching and judging one's behavior, leading to self-consciousness and concern about how one is perceived by others. In Lucinda's case, she believes that her small tear in her jeans will be noticed and laughed at by all of her classmates.