Rob Dyrdek's Fantasy Factory -- New Wood For Big Black

Rob Dyrdek's Fantasy Factory is in the middle of a major face-lift -- and it's all to make room for Big Black's new penis enhancement ... offices.

Sources close to the MTV production tell us Rob's co-star has inked a spokesman deal with Extenze male enhancement pills. We're told Big Black's new gig will require extra office space at the FF... so construction is underway and should be done before the new season premieres.