The Big Mac was an Macintosh computer with an enlarged screen.
Mac users liked the smaller computer, but were bothered by the small integrated screen. So Apple created a version with a large screen, also adding a 2-layer sandwich architecture. However, it was always running hot even when newly delivered, and was loaded with extras that users paid for but just removed. It was ultimately unpopular and discontinued. On the plus side, this avoided a nasty fight between Apple lawyers and those of Ronald McDonald.