Originated on a certain anti-chav site, used
the odd relationship apparently inbred chavs have with other
(male) members of their family. (SEE Jug Ears
. ALL chavs have jug-ears.)
Probably obviously, it derives from brother, uncle, and dad, and it has been quoted as "merely being uncle dad with 2 extra letters".
No-one, as of yet, has managed to figure out how a person might become brother, uncle, and father
all to the same
A suitably humourous female
counterpart has yet to be coined.