There are 2 main tales as to the origin of the Faff nickname.
1. So named as they are always being faffed about with by the owners wether by necessity or not.
2. Posh way of saying 5, coz it's a posh GT4 - thus the generation names as follows
165 - one-sick-five
185 - one-crate-five
205 - two-oh-faff (in a silly etonian accent for effect)
Personally, it's what we all call it and it's stuck for good. Hope this helps fella, although I'd not be at all surprised if someone has yet another answer for you. :
