CCF = Credit Card Fraud.
Basically a ccf'er is somebody that buys silk items such as astral and immortal uses them and the does something called Charge-Back.
This is against the ToS in SRO and will get your account banned, like this :
While this is not a perm ban, it is a ban for 100 years.
(I would like to add this is not my account, it was a hacked account and the guy charged back his $300 worth of silk after he was hacked.)