Zef style has strong 1980s influences and is stereotypically associated South African caucasians of low-middle social-economic status. However, it not nesessarily a derogatory term.
"It's like wearing high heels with a tracksuit. Being truly zef takes guts."
"The ultimate South African style"
The word would be used to describe the style of a particular person.
The word could also be used in a derogatory manner by someone who considered themself of higher class or better breeding.
Usually young men who drove Ford Zephyrs, hung their arm out of the window, and wore a comb stuck into one sock would be considered zef.
More recently, South African rap artists Die Antwoord and Jack Parow would be the embodiment of what zef is.
It is zef to be yourself, to be honest about your humble origins and to be proud of it.
I met this person that was zef to the max.
The club in the bad part of town is a zef place.