designated fat friend
1) someone who hangs out with someone else that is much larger then there self
2) someone who is fat and hangs out with skinny people 3) when a skinny girl hangs out with a fat girl to make her look better
This is means Destined For Fatness. It is a thin girl who will eventually become fat. The idea is that as the saying goes, when you marry a woman, look at her mom and that's what she'll look like when she gets older. This can also be loosely used to classify a girl that over eats, doe not exercise or does unhealthy things. You can either use DFF or D4 which is a thin girl that will eventually explode into a fatty.