This is an expansion on the commonly used term retard. more exclusively a shorter version of the excellent remark of F+++IN RETARD. This can be used in a wide variety of situations and is just down right hilarious.
person #1: "Hey so have you talked to soandso today?
you: "God, I hope not! last time I called him that FUCTARD talked forever and wouldnt let me off the phone!"
OR ... Man, stop acting like such a FUCTARD.