Celine is used to describe people with no life motivation. It stems from the first Celine, known to have no sleep schedule, addicted to coffee, have no control of her love life, addicted to thin pieces of wood with ink on it rather than her own life and with no bright future because of her clueless and dense mind.
Example:
Girl 1: Oh my god you look like shit, are you ok?
Girl 2: No I feel so Celine today.