ffd stands for fit from distance. It refers to when you see somebody that appears fit when looked on from far away, but when they
get closer you realize that they
aren't actually
attractive.
John: Oh mate check out that
chick across the street! She is well fit! Oh look she's crossing the
road..
James: Are you blind?! Her face looks like it's made out of leather!
John: My
bad, but to be fair she was ffd