Characters
Who's FICA? And why does he get all my money?
— Rachel ‧ Friends
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
Rachel treats the name attached to a deduction as a person receiving her money. Asking who he is makes the impersonal subtraction sound like a personal arrangement she has never agreed to. The joke rests on that mistaken identity, not on which paycheck she is examining.
Context reviewed