My favorite uncompressed file size surprise comes from the world of Dreamcast game piracy. Pirates would publish game disc images in a ZIP file that was say 10

My favorite uncompressed file size surprise comes from the world of Dreamcast game piracy. Pirates would publish game disc images in a ZIP file that was say 100mb. When uncompressed the iso file would be 750mb. The reason for the huge compression ratio was because the iso would contain a 600mb empty file, which compressed down to almost nothing. The purpose was so the when the image was burned to a cdr, the game data would be burned on the outer part of the physical media, and the empty file burned to the inner. The goal was to speed up read times when playing a game.