It's wrong to lie about being friends with someone.
Carol finds out that the boss is a huge fan of a popular band.
Carol wants to impress the boss.
Carol develops a genuine interest in the same band by listening to them a lot.
Carol mentions that she knows one of the bandmates, which is far from the truth.
Carol impresses her boss with her genuine knowledge of the band.
Carol's boss actually knows the band-mate and finds out she is lying.