In contrast with LIFE.
LIFE is what you are given when you are Conceived.
LYFF is what you earn on your own by a series of complicated decisions. Such as going to a party rather than sitting at home talking to your grandmother.
Person 1: Get a lyff
Person 2: I got one when I was born.
Person 1: Not a LIFE...a LYFF.
Person 2: WTF??
Person 1: GTFO go to a party or sumdann!