Dave,
Sorry about using our strange Antipodean words on this board, it had slipped my mind.
Gibbing, is the installation of plasterboard, which is made under the Brand name, Gibraltar Board, which has been shortened over the years to Gib board.
Oddly enough there is more than 1 type of Gib here now, they can be seen
here. Tradesmen that install Gib are called Gib-fixers and the plasterers are called Gib-stoppers down-under here.